diff --git a/4ed.cpp b/4ed.cpp
index ec75bc9a..df5977fa 100644
--- a/4ed.cpp
+++ b/4ed.cpp
@@ -54,9 +54,8 @@ file_cursor_to_end(Models *models, Editing_File *file){
 #define REQ_FILE(n,v) Editing_File *n = (v)->file_data.file; if (n == 0) return
 #define REQ_FILE_HISTORY(n,v) Editing_File *n = (v)->file_data.file; if (n == 0 || n->state.undo.undo.edits == 0) return
 
-
 DELTA_RULE_SIG(fallback_scroll_rule){
-    return(pending_delta);
+    return(pending);
 }
 
 #include "4ed_api_implementation.cpp"
@@ -339,7 +338,6 @@ App_Init_Sig(app_init){
     // NOTE(allen): live set
     Arena *arena = models->arena;
     {
-        models->live_set.node_arena = reserve_arena(models->tctx);
         models->live_set.count = 0;
         models->live_set.max = MAX_VIEWS;
         models->live_set.views = push_array(arena, View, models->live_set.max);
@@ -776,9 +774,10 @@ App_Step_Sig(app_step){
         }
     }
     
+#if 0
     // NOTE(allen): apply pending smooth deltas
     {
-        Delta_Rule_Function *scroll_rule = models->scroll_rule;
+        Delta_Rule_Function *delta_rule = models->delta_rule;
         for (Panel *panel = layout_get_first_open_panel(layout);
              panel != 0;
              panel = layout_get_next_open_panel(layout, panel)){
@@ -803,6 +802,7 @@ App_Step_Sig(app_step){
             }
         }
     }
+#endif
     
     // NOTE(allen): hook for files reloaded
     {
diff --git a/4ed_api_implementation.cpp b/4ed_api_implementation.cpp
index 6463193d..b8b08247 100644
--- a/4ed_api_implementation.cpp
+++ b/4ed_api_implementation.cpp
@@ -450,6 +450,8 @@ buffer_pos_from_relative_character(Application_Links *app,  Buffer_ID buffer_id,
     return(result);
 }
 
+
+
 api(custom) function f32
 view_line_y_difference(Application_Links *app, View_ID view_id, i64 line_a, i64 line_b){
     Models *models = (Models*)app->cmd_context;
@@ -1492,7 +1494,8 @@ view_set_cursor(Application_Links *app, View_ID view_id, Buffer_Seek seek)
 }
 
 api(custom) function b32
-view_set_buffer_scroll(Application_Links *app, View_ID view_id, Buffer_Scroll scroll)
+view_set_buffer_scroll(Application_Links *app, View_ID view_id, Buffer_Scroll scroll,
+                       Set_Buffer_Scroll_Rule rule)
 {
     Models *models = (Models*)app->cmd_context;
     b32 result = false;
@@ -1505,7 +1508,14 @@ view_set_buffer_scroll(Application_Links *app, View_ID view_id, Buffer_Scroll sc
         scroll.target.pixel_shift.x = clamp_bot(0.f, scroll.target.pixel_shift.x);
         Buffer_Layout_Item_List line = view_get_line_layout(models, view, scroll.target.line_number);
         scroll.target.pixel_shift.y = clamp(0.f, scroll.target.pixel_shift.y, line.height);
-        view_set_scroll(models, view, scroll);
+        if (rule == SetBufferScroll_SnapCursorIntoView){
+            view_set_scroll(models, view, scroll);
+        }
+        else{
+            File_Edit_Positions edit_pos = view_get_edit_pos(view);
+            edit_pos.scroll = scroll;
+            view_set_edit_pos(view, edit_pos);
+        }
         view->new_scroll_target = true;
         result = true;
     }
@@ -1580,7 +1590,7 @@ view_push_context(Application_Links *app, View_ID view_id, View_Context *ctx){
     View *view = imp_get_view(models, view_id);
     b32 result = false;
     if (api_check_view(view)){
-        view_push_context(models, view, ctx);
+        view_push_context(view, ctx);
         result = true;
     }
     return(result);
@@ -1592,7 +1602,7 @@ view_pop_context(Application_Links *app, View_ID view_id){
     View *view = imp_get_view(models, view_id);
     b32 result = false;
     if (api_check_view(view)){
-        view_pop_context(models, view);
+        view_pop_context(view);
         result = true;
     }
     return(result);
@@ -1609,6 +1619,27 @@ view_current_context(Application_Links *app, View_ID view_id){
     return(result);
 }
 
+api(custom) function Data
+view_current_context_hook_memory(Application_Links *app, View_ID view_id,
+                                 Hook_ID hook_id){
+    Models *models = (Models*)app->cmd_context;
+    View *view = imp_get_view(models, view_id);
+    Data result = {};
+    if (api_check_view(view)){
+        View_Context_Node *ctx = view_current_context_node(models, view);
+        if (ctx != 0){
+            switch (hook_id){
+                case HookID_DeltaRule:
+                {
+                    result = make_data(ctx->delta_rule_memory,
+                                       ctx->ctx.delta_rule_memory_size);
+                }break;
+            }
+        }
+    }
+    return(result);
+}
+
 function Dynamic_Workspace*
 get_dynamic_workspace(Models *models, Managed_Scope handle){
     Dynamic_Workspace *result = 0;
@@ -2062,9 +2093,9 @@ set_custom_hook(Application_Links *app, Hook_ID hook_id, Void_Func *func_ptr){
         {
             models->buffer_viewer_update = (Hook_Function*)func_ptr;
         }break;
-        case HookID_ScrollRule:
+        case HookID_DeltaRule:
         {
-            models->scroll_rule = (Delta_Rule_Function*)func_ptr;
+            models->delta_rule = (Delta_Rule_Function*)func_ptr;
         }break;
         case HookID_ViewEventHandler:
         {
@@ -2101,6 +2132,23 @@ set_custom_hook(Application_Links *app, Hook_ID hook_id, Void_Func *func_ptr){
     }
 }
 
+api(custom) function b32
+set_custom_hook_memory_size(Application_Links *app, Hook_ID hook_id, umem size){
+    Models *models = (Models*)app->cmd_context;
+    b32 result = true;
+    switch (hook_id){
+        case HookID_DeltaRule:
+        {
+            models->delta_rule_memory_size = size;
+        }break;
+        default:
+        {
+            result = false;
+        }break;
+    }
+    return(result);
+}
+
 api(custom) function Mouse_State
 get_mouse_state(Application_Links *app)
 {
diff --git a/4ed_app_models.h b/4ed_app_models.h
index 24423c37..ecdb6ae7 100644
--- a/4ed_app_models.h
+++ b/4ed_app_models.h
@@ -52,10 +52,12 @@ struct Models{
     
     Application_Links app_links;
     
-    Hook_Function *buffer_viewer_update;
-    Delta_Rule_Function *scroll_rule;
-    Custom_Command_Function *view_event_handler;
     Render_Caller_Function *render_caller;
+    Delta_Rule_Function *delta_rule;
+    umem delta_rule_memory_size;
+    
+    Hook_Function *buffer_viewer_update;
+    Custom_Command_Function *view_event_handler;
     Buffer_Name_Resolver_Function *buffer_name_resolver;
     Buffer_Hook_Function *begin_buffer;
     Buffer_Hook_Function *end_buffer;
diff --git a/4ed_view.cpp b/4ed_view.cpp
index daec613a..a8551da2 100644
--- a/4ed_view.cpp
+++ b/4ed_view.cpp
@@ -453,39 +453,30 @@ view_set_file(Models *models, View *view, Editing_File *file){
 
 ////////////////////////////////
 
-function View_Context_Node*
-view__alloc_context_node(Live_Views *views){
-    View_Context_Node *node = views->free_nodes;
-    if (node != 0){
-        sll_stack_pop(views->free_nodes); 
-    }
-    else{
-        node = push_array(views->node_arena, View_Context_Node, 1);
-    }
-    return(node);
-}
-
 function void
-view__free_context_node(Live_Views *views, View_Context_Node *node){
-    sll_stack_push(views->free_nodes, node);
-}
-
-function void
-view_push_context(Models *models, View *view, View_Context *ctx){
-    View_Context_Node *node = view__alloc_context_node(&models->live_set);
+view_push_context(View *view, View_Context *ctx){
+    Temp_Memory pop_me = begin_temp(view->node_arena);
+    View_Context_Node *node = push_array_zero(view->node_arena, View_Context_Node, 1);
     sll_stack_push(view->ctx, node);
+    node->pop_me = pop_me;
     block_copy_struct(&node->ctx, ctx);
+    node->delta_rule_memory = push_array_zero(view->node_arena, u8, ctx->delta_rule_memory_size);
 }
 
 function void
-view_pop_context(Models *models, View *view){
+view_pop_context(View *view){
     View_Context_Node *node = view->ctx;
-    if (node != 0){
+    if (node != 0 && node->next != 0){
         sll_stack_pop(view->ctx);
-        view__free_context_node(&models->live_set, node);
+        end_temp(node->pop_me);
     }
 }
 
+function View_Context_Node*
+view_current_context_node(Models *models, View *view){
+    return(view->ctx);
+}
+
 function View_Context
 view_current_context(Models *models, View *view){
     View_Context ctx = {};
@@ -566,9 +557,13 @@ view_init(Models *models, View *view, Editing_File *initial_buffer,
           Custom_Command_Function *event_context_base){
     view_set_file(models, view, initial_buffer);
     
+    view->node_arena = reserve_arena(models->tctx);
+    
     View_Context first_ctx = {};
     first_ctx.render_caller = models->render_caller;
-    view_push_context(models, view, &first_ctx);
+    first_ctx.delta_rule = models->delta_rule;
+    first_ctx.delta_rule_memory_size = models->delta_rule_memory_size;
+    view_push_context(view, &first_ctx);
     
     view->co = coroutine_create(&models->coroutines, view_event_context_base__inner);
     Co_In in = {};
diff --git a/4ed_view.h b/4ed_view.h
index 26c8ee62..3d2c1947 100644
--- a/4ed_view.h
+++ b/4ed_view.h
@@ -58,7 +58,9 @@ struct Query_Set{
 
 struct View_Context_Node{
     View_Context_Node *next;
+    Temp_Memory pop_me;
     View_Context ctx;
+    void *delta_rule_memory;
 };
 
 struct View{
@@ -79,6 +81,7 @@ struct View{
     Coroutine *co;
     Co_Out co_out;
     
+    Arena *node_arena;
     View_Context_Node *ctx;
     
     b8 hide_scrollbar;
@@ -89,8 +92,6 @@ struct View{
 };
 
 struct Live_Views{
-    Arena *node_arena;
-    View_Context_Node *free_nodes;
     View *views;
     View free_sentinel;
     i32 count;
diff --git a/custom/4coder_base_commands.cpp b/custom/4coder_base_commands.cpp
index 40bb30b4..8c16e6e8 100644
--- a/custom/4coder_base_commands.cpp
+++ b/custom/4coder_base_commands.cpp
@@ -207,7 +207,7 @@ CUSTOM_DOC("Centers the view vertically on the line on which the cursor sits.")
     Buffer_Scroll scroll = view_get_buffer_scroll(app, view);
     scroll.target.line_number = cursor.line;
     scroll.target.pixel_shift.y = -view_height*0.5f;
-    view_set_buffer_scroll(app, view, scroll);
+    view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
 }
 
 CUSTOM_COMMAND_SIG(left_adjust_view)
@@ -219,7 +219,7 @@ CUSTOM_DOC("Sets the left size of the view near the x position of the cursor.")
     Vec2_f32 p = view_relative_xy_of_pos(app, view, cursor.line, pos);
     Buffer_Scroll scroll = view_get_buffer_scroll(app, view);
     scroll.target.pixel_shift.x = clamp_bot(0.f, p.x - 30.f);
-    view_set_buffer_scroll(app, view, scroll);
+    view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
 }
 
 CUSTOM_COMMAND_SIG(click_set_cursor_and_mark)
@@ -272,7 +272,7 @@ CUSTOM_DOC("Reads the scroll wheel value from the mouse state and scrolls accord
     if (mouse.wheel != 0){
         Buffer_Scroll scroll = view_get_buffer_scroll(app, view);
         scroll.target = view_move_buffer_point(app, view, scroll.target, V2f32(0.f, (f32)mouse.wheel));
-        view_set_buffer_scroll(app, view, scroll);
+        view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
     }
 }
 
@@ -1581,10 +1581,10 @@ CUSTOM_DOC("Set the other non-active panel to view the buffer that the active pa
             
             view_set_cursor_and_preferred_x(app, view1, seek_pos(p2));
             view_set_mark(app, view1, seek_pos(m2));
-            view_set_buffer_scroll(app, view1, sc2);
+            view_set_buffer_scroll(app, view1, sc2, SetBufferScroll_SnapCursorIntoView);
             view_set_cursor_and_preferred_x(app, view2, seek_pos(p1));
             view_set_mark(app, view2, seek_pos(m1));
-            view_set_buffer_scroll(app, view2, sc1);
+            view_set_buffer_scroll(app, view2, sc1, SetBufferScroll_SnapCursorIntoView);
         }
     }
 }
diff --git a/custom/4coder_base_types.cpp b/custom/4coder_base_types.cpp
index ca75b0fb..22c90389 100644
--- a/custom/4coder_base_types.cpp
+++ b/custom/4coder_base_types.cpp
@@ -2438,6 +2438,46 @@ rect_union(Rect_f32 a, Rect_f32 b){
 
 ////////////////////////////////
 
+internal Rect_f32_Pair
+rect_split_top_bottom(Rect_f32 rect, f32 y){
+    y = clamp(rect.y0, y, rect.y1);
+    Rect_f32_Pair pair = {};
+    pair.a = Rf32(rect.x0, rect.y0, rect.x1, y      );
+    pair.b = Rf32(rect.x0, y      , rect.x1, rect.y1);
+    return(pair);
+}
+
+internal Rect_f32_Pair
+rect_split_left_right(Rect_f32 rect, f32 x){
+    x = clamp(rect.x0, x, rect.x1);
+    Rect_f32_Pair pair = {};
+    pair.a = Rf32(rect.x0, rect.y0, x      , rect.y1);
+    pair.b = Rf32(x      , rect.y0, rect.x1, rect.y1);
+    return(pair);
+}
+
+internal Rect_f32_Pair
+rect_split_top_bottom_neg(Rect_f32 rect, f32 y){
+    return(rect_split_top_bottom(rect, rect.y1 - y));
+}
+
+internal Rect_f32_Pair
+rect_split_left_right_neg(Rect_f32 rect, f32 x){
+    return(rect_split_left_right(rect, rect.x1 - x));
+}
+
+internal Rect_f32_Pair
+rect_split_top_bottom_lerp(Rect_f32 rect, f32 t){
+    return(rect_split_top_bottom(rect, lerp(rect.y0, t, rect.y1)));
+}
+
+internal Rect_f32_Pair
+rect_split_left_right_lerp(Rect_f32 rect, f32 t){
+    return(rect_split_left_right(rect, lerp(rect.x0, t, rect.x1)));
+}
+
+////////////////////////////////
+
 internal Scan_Direction
 flip_direction(Scan_Direction direction){
     switch (direction){
diff --git a/custom/4coder_base_types.h b/custom/4coder_base_types.h
index 98ac7903..bfd44934 100644
--- a/custom/4coder_base_types.h
+++ b/custom/4coder_base_types.h
@@ -760,8 +760,18 @@ typedef Vec2_f32 Vec2;
 typedef Vec3_f32 Vec3;
 typedef Vec4_f32 Vec4;
 
-struct Rect_f32_Pair{
-    Rect_f32 e[2];
+union Rect_f32_Pair{
+    struct{
+        Rect_f32 a;
+        Rect_f32 b;
+    };
+    struct{
+        Rect_f32 min;
+        Rect_f32 max;
+    };
+    struct{
+        Rect_f32 e[2];
+    };
 };
 
 ////////////////////////////////
diff --git a/custom/4coder_default_hooks.cpp b/custom/4coder_default_hooks.cpp
index e518e92d..fb3bbb5f 100644
--- a/custom/4coder_default_hooks.cpp
+++ b/custom/4coder_default_hooks.cpp
@@ -278,21 +278,31 @@ MODIFY_COLOR_TABLE_SIG(default_modify_color_table){
 }
 #endif
 
+function Rect_f32_Pair
+layout_file_bar_on_top(Rect_f32 rect, f32 line_height){
+    return(rect_split_top_bottom(rect, line_height + 2.f));
+}
+
+function Rect_f32_Pair
+layout_file_bar_on_bot(Rect_f32 rect, f32 line_height){
+    return(rect_split_top_bottom_neg(rect, line_height + 2.f));
+}
+
 function Rect_f32
-default_view_buffer_region(Application_Links *app, View_ID view_id, Rect_f32 sub_region){
+default_buffer_region(Application_Links *app, View_ID view_id, Rect_f32 region){
+    region = rect_inner(region, 3.f);
+    
     Buffer_ID buffer = view_get_buffer(app, view_id, AccessAll);
     Face_ID face_id = get_face_id(app, buffer);
     Face_Metrics metrics = get_face_metrics(app, face_id);
-    i32 line_height = i32_ceil32(metrics.line_height);
+    f32  line_height = metrics.line_height;
     
     // file bar
-    {
-        b64 showing_file_bar = false;
-        if (view_get_setting(app, view_id, ViewSetting_ShowFileBar, &showing_file_bar)){
-            if (showing_file_bar){
-                sub_region.y0 += line_height + 2;
-            }
-        }
+    b64 showing_file_bar = false;
+    if (view_get_setting(app, view_id, ViewSetting_ShowFileBar, &showing_file_bar) &&
+        showing_file_bar){
+        Rect_f32_Pair pair = layout_file_bar_on_top(region, line_height);
+        region = pair.b;
     }
     
     // query bar
@@ -301,8 +311,8 @@ default_view_buffer_region(Application_Links *app, View_ID view_id, Rect_f32 sub
         Query_Bar_Ptr_Array query_bars = {};
         query_bars.ptrs = space;
         if (get_active_query_bars(app, view_id, ArrayCount(space), &query_bars)){
-            i32 widget_height = (line_height + 2)*query_bars.count;
-            sub_region.y0 += widget_height;
+            f32 widget_height = (line_height + 2)*query_bars.count;
+            region.y0 += widget_height;
         }
     }
     
@@ -311,10 +321,10 @@ default_view_buffer_region(Application_Links *app, View_ID view_id, Rect_f32 sub
         i64 line_count = buffer_get_line_count(app, buffer);
         i64 line_count_digit_count = digit_count_from_integer(line_count, 10);
         i32 margin_width = i32_ceil32((f32)line_count_digit_count*metrics.normal_advance);
-        sub_region.x0 += margin_width + 2;
+        region.x0 += margin_width + 2;
     }
     
-    return(sub_region);
+    return(region);
 }
 
 internal int_color
@@ -447,10 +457,36 @@ default_render_caller(Application_Links *app, Frame_Info frame_info, View_ID vie
         draw_fancy_string(app, face_id, list.first, p, Stag_Default, 0);
     }
     
-    Rect_f32 sub_region = default_view_buffer_region(app, view_id, inner);
-    Rect_f32 buffer_rect = rect_intersect(sub_region, inner);
-    
+    Rect_f32 buffer_rect = default_buffer_region(app, view_id, view_rect);
     Buffer_Scroll scroll = view_get_buffer_scroll(app, view_id);
+    
+    Buffer_Point_Delta_Result delta = delta_apply(app, view_id,
+                                                  frame_info.animation_dt, scroll);
+    if (!block_match_struct(&scroll.position, &delta.point)){
+        block_copy_struct(&scroll.position, &delta.point);
+        view_set_buffer_scroll(app, view_id, scroll, SetBufferScroll_NoCursorChange);
+    }
+    if (delta.still_animating){
+        animate_in_n_milliseconds(app, 0);
+    }
+    
+#if 0    
+    // NOTE(allen): clamp scroll target and position; smooth scroll rule
+    {
+        Vec2_f32 pending = view_point_difference(app, view_id, scroll.target, scroll.position);
+        if (!near_zero(pending, 0.5f)){
+            // TODO(allen): use the real delta rule from the context
+            Vec2_f32 partial = pending;
+            scroll.position = view_move_buffer_point(app, view_id, scroll.position, partial);
+            animate_in_n_milliseconds(app, 0);
+        }
+        else{
+            scroll.position = scroll.target;
+        }
+        view_set_buffer_scroll(app, view_id, scroll, SetBufferScroll_NoCursorChange);
+    }
+#endif
+    
     Buffer_Point buffer_point = scroll.position;
     Text_Layout_ID text_layout_id = text_layout_create(app, buffer, buffer_rect, buffer_point);
     Interval_i64 visible_range = text_layout_get_visible_range(app, text_layout_id);
@@ -762,8 +798,8 @@ default_render_caller(Application_Links *app, Frame_Info frame_info, View_ID vie
 }
 
 HOOK_SIG(default_view_adjust){
-    // NOTE(allen): Called whenever the view layout/sizes have been modified, including
-    // by full window resize.
+    // NOTE(allen): Called whenever the view layout/sizes have been modified,
+    // including by full window resize.
     return(0);
 }
 
@@ -1120,85 +1156,6 @@ BUFFER_HOOK_SIG(default_end_file){
     return(0);
 }
 
-// TODO(allen): FIX FIX FIX FIX
-// NOTE(allen|a4): scroll rule information
-//
-// The parameters:
-// target_x, target_y
-//  This is where the view would like to be for the purpose of
-// following the cursor, doing mouse wheel work, etc.
-//
-// scroll_x, scroll_y
-//  These are pointers to where the scrolling actually is. If you bind
-// the scroll rule it is you have to update these in some way to move
-// the actual location of the scrolling.
-//
-// view_id
-//  This corresponds to which view is computing it's new scrolling position.
-// This id DOES correspond to the views that View_ _Summary contains.
-// This will always be between 1 and 16 (0 is a null id).
-// See below for an example of having state that carries across scroll udpates.
-//
-// is_new_target
-//  If the target of the view is different from the last target in either x or y
-// this is true, otherwise it is false.
-//
-// The return:
-//  Should be true if and only if scroll_x or scroll_y are changed.
-//
-// Don't try to use the app pointer in a scroll rule, you're asking for trouble.
-//
-// If you don't bind scroll_rule, nothing bad will happen, yo will get default
-// 4coder scrolling behavior.
-//
-
-Vec2_f32 scroll_velocity_[16] = {};
-Vec2_f32 *scroll_velocity = scroll_velocity_ - 1;
-
-struct Smooth_Step{
-    f32 p;
-    f32 v;
-};
-
-internal Smooth_Step
-smooth_camera_step(f32 target, f32 v, f32 S, f32 T){
-    Smooth_Step step = {};
-    step.v = v;
-    if (step.p != target){
-        if (step.p > target - .1f && step.p < target + .1f){
-            step.p = target;
-            step.v = 1.f;
-        }
-        else{
-            f32 L = step.p + T*(target - step.p);
-            i32 sign = (target > step.p) - (target < step.p);
-            f32 V = step.p + sign*step.v;
-            if (sign > 0){
-                step.p = (L<V)?(L):(V);
-            }
-            else{
-                step.p = (L>V)?(L):(V);
-            }
-            if (step.p == V){
-                step.v *= S;
-            }
-        }
-    }
-    return(step);
-}
-
-DELTA_RULE_SIG(smooth_scroll_rule){
-    Vec2_f32 *velocity = scroll_velocity + view_id;
-    if (velocity->x == 0.f){
-        velocity->x = 1.f;
-        velocity->y = 1.f;
-    }
-    Smooth_Step step_x = smooth_camera_step(pending_delta.x, velocity->x, 80.f, 1.f/2.f);
-    Smooth_Step step_y = smooth_camera_step(pending_delta.y, velocity->y, 80.f, 1.f/2.f);
-    *velocity = V2f32(step_x.v, step_y.v);
-    return(V2f32(step_x.p, step_y.p));
-}
-
 internal void
 set_all_default_hooks(Application_Links *app){
 #if 0
@@ -1213,7 +1170,15 @@ set_all_default_hooks(Application_Links *app){
     
     set_custom_hook(app, HookID_ViewEventHandler, default_view_input_handler);
     set_custom_hook(app, HookID_RenderCaller, default_render_caller);
-    set_custom_hook(app, HookID_ScrollRule, smooth_scroll_rule);
+#if 0
+    set_custom_hook(app, HookID_DeltaRule, original_delta);
+    set_custom_hook_memory_size(app, HookID_DeltaRule,
+                                delta_ctx_size(original_delta_memory_size));
+#else
+    set_custom_hook(app, HookID_DeltaRule, fixed_time_cubic_delta);
+    set_custom_hook_memory_size(app, HookID_DeltaRule,
+                                delta_ctx_size(fixed_time_cubic_delta_memory_size));
+#endif
     set_custom_hook(app, HookID_BufferNameResolver, default_buffer_name_resolution);
     
     set_custom_hook(app, HookID_BeginBuffer, default_file_settings);
@@ -1221,7 +1186,7 @@ set_all_default_hooks(Application_Links *app){
     set_custom_hook(app, HookID_NewFile, default_new_file);
     set_custom_hook(app, HookID_SaveFile, default_file_save);
     set_custom_hook(app, HookID_BufferEditRange, default_buffer_edit_range);
-    set_custom_hook(app, HookID_BufferRegion, default_view_buffer_region);
+    set_custom_hook(app, HookID_BufferRegion, default_buffer_region);
 }
 
 // BOTTOM
diff --git a/custom/4coder_default_include.cpp b/custom/4coder_default_include.cpp
index 13359933..365973b3 100644
--- a/custom/4coder_default_include.cpp
+++ b/custom/4coder_default_include.cpp
@@ -29,6 +29,7 @@
 #include "4coder_command_map.h"
 #include "4coder_string_match.h"
 #include "4coder_helper.h"
+#include "4coder_delta_rule.h"
 #include "4coder_insertion.h"
 #include "4coder_fancy.h"
 #include "4coder_lister_base.h"
@@ -66,6 +67,7 @@
 #include "4coder_command_map.cpp"
 #include "4coder_default_framework_variables.cpp"
 #include "4coder_helper.cpp"
+#include "4coder_delta_rule.cpp"
 #include "4coder_fancy.cpp"
 #include "4coder_lister_base.cpp"
 #include "4coder_font_helper.cpp"
diff --git a/custom/4coder_delta_rule.cpp b/custom/4coder_delta_rule.cpp
new file mode 100644
index 00000000..ce7bf7ef
--- /dev/null
+++ b/custom/4coder_delta_rule.cpp
@@ -0,0 +1,218 @@
+/*
+4coder_delta_rule.cpp - Built in delta rules and delta rule helpers.
+*/
+
+// TOP
+
+function umem
+delta_ctx_size(umem base_size){
+    return(base_size + sizeof(Delta_Context_Header));
+}
+
+function Delta_Context_Header*
+delta_ctx_get_header(Data delta_ctx){
+    return((Delta_Context_Header*)delta_ctx.data);
+}
+
+function void*
+delta_ctx_get_user_data(Data delta_ctx){
+    Delta_Context_Header *ctx = (Delta_Context_Header*)delta_ctx.data;
+    return(ctx + 1);
+}
+
+function Buffer_Point_Delta_Result
+delta_apply(Application_Links *app, View_ID view,
+            Delta_Rule_Function *func, Data delta_ctx,
+            f32 dt, Buffer_Point position, Buffer_Point target){
+    Buffer_Point_Delta_Result result = {};
+    Vec2_f32 pending = view_point_difference(app, view, target, position);
+    if (!near_zero(pending, 0.5f)){
+        Delta_Context_Header *ctx = delta_ctx_get_header(delta_ctx);
+        b32 is_new_target = false;
+        if (!block_match_struct(&ctx->point, &target)){
+            block_copy_struct(&ctx->point, &target);
+            is_new_target = true;
+        }
+        void *rule_data = delta_ctx_get_user_data(delta_ctx);
+        Vec2_f32 partial = func(pending, is_new_target, dt, rule_data);
+        
+        // NOTE(allen): clamp partial into the box from the origin
+        // to the pending delta.
+        Range_f32 x = If32(pending.x, 0.f);
+        Range_f32 y = If32(pending.y, 0.f);
+        partial.x = clamp_range(x, partial.x);
+        partial.y = clamp_range(y, partial.y);
+        
+        result.point = view_move_buffer_point(app, view, position, partial);
+        result.still_animating = true;
+    }
+    else{
+        result.point = target;
+    }
+    return(result);
+}
+
+function Buffer_Point_Delta_Result
+delta_apply(Application_Links *app, View_ID view, 
+            Delta_Rule_Function *func, Data delta_ctx,
+            f32 dt, Buffer_Scroll scroll){
+    return(delta_apply(app, view, func, delta_ctx,
+                       dt, scroll.position, scroll.target));
+}
+
+function Buffer_Point_Delta_Result
+delta_apply(Application_Links *app, View_ID view, 
+            f32 dt, Buffer_Point position, Buffer_Point target){
+    View_Context ctx = view_current_context(app, view);
+    Data delta_ctx = view_current_context_hook_memory(app, view, HookID_DeltaRule);
+    return(delta_apply(app, view, ctx.delta_rule, delta_ctx,
+                       dt, position, target));
+}
+
+function Buffer_Point_Delta_Result
+delta_apply(Application_Links *app, View_ID view, 
+            f32 dt, Buffer_Scroll scroll){
+    View_Context ctx = view_current_context(app, view);
+    Data delta_ctx = view_current_context_hook_memory(app, view, HookID_DeltaRule);
+    return(delta_apply(app, view, ctx.delta_rule, delta_ctx,
+                       dt, scroll.position, scroll.target));
+}
+
+function Vec2_f32_Delta_Result
+delta_apply(Application_Links *app, View_ID view,
+            Delta_Rule_Function *func, Data delta_ctx,
+            f32 dt, Vec2_f32 position, Vec2_f32 target){
+    Vec2_f32_Delta_Result result = {};
+    Vec2_f32 pending = target - position;
+    if (!near_zero(pending, 0.5f)){
+        Delta_Context_Header *ctx = delta_ctx_get_header(delta_ctx);
+        b32 is_new_target = false;
+        if (!near_zero(ctx->p - target, 0.1f)){
+            block_copy_struct(&ctx->p, &target);
+            is_new_target = true;
+        }
+        void *rule_data = delta_ctx_get_user_data(delta_ctx);
+        Vec2_f32 partial = func(pending, is_new_target, dt, rule_data);
+        
+        // NOTE(allen): clamp partial into the box from the origin
+        // to the pending delta.
+        Range_f32 x = If32(pending.x, 0.f);
+        Range_f32 y = If32(pending.y, 0.f);
+        partial.x = clamp_range(x, partial.x);
+        partial.y = clamp_range(y, partial.y);
+        
+        result.p = position + partial;
+        result.still_animating = true;
+    }
+    else{
+        result.p = target;
+    }
+    return(result);
+}
+
+function Vec2_f32_Delta_Result
+delta_apply(Application_Links *app, View_ID view,
+            Delta_Rule_Function *func, Data delta_ctx,
+            f32 dt, Basic_Scroll scroll){
+    return(delta_apply(app, view, func, delta_ctx,
+                       dt, scroll.position, scroll.target));
+}
+
+function Vec2_f32_Delta_Result
+delta_apply(Application_Links *app, View_ID view, 
+            f32 dt, Vec2_f32 position, Vec2_f32 target){
+    View_Context ctx = view_current_context(app, view);
+    Data delta_ctx = view_current_context_hook_memory(app, view, HookID_DeltaRule);
+    return(delta_apply(app, view, ctx.delta_rule, delta_ctx,
+                       dt, position, target));
+}
+
+function Vec2_f32_Delta_Result
+delta_apply(Application_Links *app, View_ID view, 
+            f32 dt, Basic_Scroll scroll){
+    View_Context ctx = view_current_context(app, view);
+    Data delta_ctx = view_current_context_hook_memory(app, view, HookID_DeltaRule);
+    return(delta_apply(app, view, ctx.delta_rule, delta_ctx,
+                       dt, scroll.position, scroll.target));
+}
+
+////////////////////////////////
+
+internal Smooth_Step
+smooth_camera_step(f32 target, f32 v, f32 S, f32 T){
+    Smooth_Step step = {};
+    step.v = v;
+    if (step.p != target){
+        if (step.p > target - .1f && step.p < target + .1f){
+            step.p = target;
+            step.v = 1.f;
+        }
+        else{
+            f32 L = step.p + T*(target - step.p);
+            i32 sign = (target > step.p) - (target < step.p);
+            f32 V = step.p + sign*step.v;
+            if (sign > 0){
+                step.p = (L<V)?(L):(V);
+            }
+            else{
+                step.p = (L>V)?(L):(V);
+            }
+            if (step.p == V){
+                step.v *= S;
+            }
+        }
+    }
+    return(step);
+}
+DELTA_RULE_SIG(original_delta){
+    Vec2_f32 *velocity = (Vec2_f32*)data;
+    if (velocity->x == 0.f){
+        velocity->x = 1.f;
+        velocity->y = 1.f;
+    }
+    Smooth_Step step_x = smooth_camera_step(pending.x, velocity->x, 80.f, 1.f/2.f);
+    Smooth_Step step_y = smooth_camera_step(pending.y, velocity->y, 80.f, 1.f/2.f);
+    *velocity = V2f32(step_x.v, step_y.v);
+    return(V2f32(step_x.p, step_y.p));
+}
+global_const umem original_delta_memory_size = sizeof(Vec2_f32);
+
+DELTA_RULE_SIG(snap_delta){
+    return(pending);
+}
+global_const umem snap_delta_memory_size = 0;
+
+function f32
+cubic_reinterpolate(f32 t){
+    f32 t2 = t*t;
+    f32 t3 = t2*t;
+    return(3*t2 - 2*t3);
+}
+DELTA_RULE_SIG(fixed_time_cubic_delta){
+    local_const f32 duration_in_seconds = (1.f/8.f);
+    local_const f32 dt_multiplier = 1.f/duration_in_seconds;
+    f32 step = dt*dt_multiplier;
+    f32 *t = (f32*)data;
+    *t = clamp(0.f, *t, 1.f);
+    f32 prev_t = *t;
+    if (is_new_target){
+        prev_t = 0.f;
+        *t = step;
+    }
+    else{
+        *t += step;
+    }
+    *t = clamp(0.f, *t, 1.f);
+    Vec2_f32 result = pending;
+    if (*t < 1.f){
+        f32 prev_x = cubic_reinterpolate(prev_t);
+        f32 x = cubic_reinterpolate(*t);
+        f32 portion = ((x - prev_x)/(1.f - prev_x));
+        result *= portion;
+    }
+    return(result);
+}
+global_const umem fixed_time_cubic_delta_memory_size = sizeof(f32);
+
+// BOTTOM
+
diff --git a/custom/4coder_delta_rule.h b/custom/4coder_delta_rule.h
new file mode 100644
index 00000000..51d3c5f8
--- /dev/null
+++ b/custom/4coder_delta_rule.h
@@ -0,0 +1,31 @@
+/*
+4coder_delta_rule.h - Types for built in delta rules and delta rule helpers.
+*/
+
+// TOP
+
+#if !defined(FCODER_DELTA_RULE_H)
+#define FCODER_DELTA_RULE_H
+
+union Delta_Context_Header{
+    Buffer_Point point;
+    Vec2_f32 p;
+};
+struct Buffer_Point_Delta_Result{
+    Buffer_Point point;
+    b32 still_animating;
+};
+struct Vec2_f32_Delta_Result{
+    Vec2_f32 p;
+    b32 still_animating;
+};
+
+struct Smooth_Step{
+    f32 p;
+    f32 v;
+};
+
+#endif
+
+// BOTTOM
+
diff --git a/custom/4coder_helper.cpp b/custom/4coder_helper.cpp
index 998c7f1f..96163ce4 100644
--- a/custom/4coder_helper.cpp
+++ b/custom/4coder_helper.cpp
@@ -167,7 +167,7 @@ view_move_buffer_point(Application_Links *app, View_ID view, Buffer_Point buffer
 internal void
 view_zero_scroll(Application_Links *app, View_ID view){
     Buffer_Scroll scroll = {};
-    view_set_buffer_scroll(app, view, scroll);
+    view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
 }
 
 internal void
@@ -178,6 +178,23 @@ view_set_cursor_and_preferred_x(Application_Links *app, View_ID view, Buffer_See
     view_set_preferred_x(app, view, p.x);
 }
 
+function Vec2_f32
+buffer_point_difference(Application_Links *app, Buffer_ID buffer, f32 width, Face_ID face_id,
+                        Buffer_Point a, Buffer_Point b){
+    f32 y_difference = buffer_line_y_difference(app, buffer, width, face_id, a.line_number, b.line_number);
+    Vec2_f32 result = a.pixel_shift - b.pixel_shift;
+    result.y += y_difference;
+    return(result);
+}
+
+function Vec2_f32
+view_point_difference(Application_Links *app, View_ID view, Buffer_Point a, Buffer_Point b){
+    f32 y_difference = view_line_y_difference(app, view, a.line_number, b.line_number);
+    Vec2_f32 result = a.pixel_shift - b.pixel_shift;
+    result.y += y_difference;
+    return(result);
+}
+
 ////////////////////////////////
 
 internal Range_i64
@@ -1625,7 +1642,7 @@ view_look_at_region(Application_Links *app, View_ID view, i64 major_pos, i64 min
                 Buffer_Scroll scroll = view_get_buffer_scroll(app, view);
                 scroll.target.line_number = major_line;
                 scroll.target.pixel_shift.y = -skirt_height;
-                view_set_buffer_scroll(app, view, scroll);
+                view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
             }
             else{
                 Buffer_Scroll scroll = view_get_buffer_scroll(app, view);
@@ -1634,7 +1651,7 @@ view_look_at_region(Application_Links *app, View_ID view, i64 major_pos, i64 min
                 if (top_p.y < acceptable_y.min){
                     scroll.target.line_number = top.line;
                     scroll.target.pixel_shift.y = -skirt_height;
-                    view_set_buffer_scroll(app, view, scroll);
+                    view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
                 }
                 else{
                     Vec2_f32 bot_p = view_relative_xy_of_pos(app, view, scroll.position.line_number, range.max);
@@ -1642,7 +1659,7 @@ view_look_at_region(Application_Links *app, View_ID view, i64 major_pos, i64 min
                     if (bot_p.y > acceptable_y.max){
                         scroll.target.line_number = bottom.line;
                         scroll.target.pixel_shift.y = skirt_height - view_height;
-                        view_set_buffer_scroll(app, view, scroll);
+                        view_set_buffer_scroll(app, view, scroll, SetBufferScroll_SnapCursorIntoView);
                     }
                 }
             }
diff --git a/custom/4coder_lister_base.cpp b/custom/4coder_lister_base.cpp
index fc8143b3..a79fdf9c 100644
--- a/custom/4coder_lister_base.cpp
+++ b/custom/4coder_lister_base.cpp
@@ -139,6 +139,11 @@ lister_append_key(Lister *lister, char *string){
     lister_append_string(SCu8(string), &lister->key_string);
 }
 
+function void
+lister_zero_scroll(Lister *lister){
+    block_zero_struct(&lister->scroll);
+}
+
 function void
 lister_render(Application_Links *app, Frame_Info frame_info, View_ID view){
     Scratch_Block scratch(app);
@@ -171,6 +176,9 @@ lister_render(Application_Links *app, Frame_Info frame_info, View_ID view){
     f32 block_height = lister_get_block_height(line_height);
     f32 text_field_height = lister_get_text_field_height(line_height);
     
+    lister->visible_count = (i32)((rect_height(region)/block_height)) - 3;
+    lister->visible_count = clamp_bot(1, lister->visible_count);
+    
     Lister_Top_Level_Layout layout = lister_get_top_level_layout(region, text_field_height);
     
     {
@@ -188,19 +196,48 @@ lister_render(Application_Links *app, Frame_Info frame_info, View_ID view){
     Range_f32 x = rect_range_x(layout.list_rect);
     draw_set_clip(app, layout.list_rect);
     
+    // NOTE(allen): auto scroll to the item if the flag is set.
+    f32 scroll_y = lister->scroll.position.y;
+    
+    if (lister->set_vertical_focus_to_item){
+        lister->set_vertical_focus_to_item = false;
+        Range_f32 item_y = If32_size(lister->item_index*block_height, block_height);
+        f32 view_h = rect_height(layout.list_rect);
+        Range_f32 view_y = If32_size(scroll_y, view_h);
+        if (view_y.min > item_y.min || item_y.max > view_y.max){
+            f32 item_center = (item_y.min + item_y.max)*0.5f;
+            f32 view_center = (view_y.min + view_y.max)*0.5f;
+            f32 margin = view_h*.3f;
+            margin = clamp_top(margin, block_height*3.f);
+            if (item_center < view_center){
+                lister->scroll.target.y = item_y.min - margin;
+            }
+            else{
+                f32 target_bot = item_y.max + margin;
+                lister->scroll.target.y = target_bot - view_h;
+            }
+        }
+    }
+    
+    // NOTE(allen): clamp scroll target and position; smooth scroll rule
     i32 count = lister->filtered.count;
     Range_f32 scroll_range = If32(0.f, clamp_bot(0.f, count*block_height - block_height));
-    lister->scroll.position.y = clamp_range(scroll_range, lister->scroll.position.y);
-    lister->scroll.position.x = 0.f;
     lister->scroll.target.y = clamp_range(scroll_range, lister->scroll.target.y);
     lister->scroll.target.x = 0.f;
     
-    // TODO(allen): get scroll rule from context
-    lister->scroll.position = lister->scroll.target;
+    Vec2_f32_Delta_Result delta = delta_apply(app, view,
+                                              frame_info.animation_dt, lister->scroll);
+    lister->scroll.position = delta.p;
+    if (delta.still_animating){
+        animate_in_n_milliseconds(app, 0);
+    }
     
-    f32 scroll_y = lister->scroll.position.y;
+    lister->scroll.position.y = clamp_range(scroll_range, lister->scroll.position.y);
+    lister->scroll.position.x = 0.f;
     
+    scroll_y = lister->scroll.position.y;
     f32 y_pos = layout.list_rect.y0 - scroll_y;
+    
     i32 first_index = (i32)(scroll_y/block_height);
     y_pos += first_index*block_height;
     
@@ -308,6 +345,20 @@ lister_get_filtered(Arena *arena, Lister *lister){
     return(filtered);
 }
 
+function void
+lister_update_selection_values(Lister *lister){
+    lister->raw_item_index = -1;
+    lister->highlighted_node = 0;
+    i32 count = lister->filtered.count;
+    for (i32 i = 0; i < count; i += 1){
+        Lister_Node *node = lister->filtered.node_ptrs[i];
+        if (lister->item_index == i){
+            lister->highlighted_node = node;
+            lister->raw_item_index = node->raw_index;
+        }
+    }
+}
+
 function void
 lister_update_filtered_list(Application_Links *app, View_ID view, Lister *lister){
     Scratch_Block scratch(app, Scratch_Share);
@@ -332,23 +383,17 @@ lister_update_filtered_list(Application_Links *app, View_ID view, Lister *lister
     Lister_Node **node_ptrs = push_array(arena, Lister_Node*, total_count);
     lister->filtered.node_ptrs = node_ptrs;
     lister->filtered.count = total_count;
-    
-    lister->raw_item_index = -1;
-    lister->highlighted_node = 0;
-    
     i32 counter = 0;
     for (i32 array_index = 0; array_index < ArrayCount(node_ptr_arrays); array_index += 1){
         Lister_Node_Ptr_Array node_ptr_array = node_ptr_arrays[array_index];
         for (i32 node_index = 0; node_index < node_ptr_array.count; node_index += 1){
             Lister_Node *node = node_ptr_array.node_ptrs[node_index];
             node_ptrs[counter] = node;
-            if (lister->item_index == counter){
-                lister->highlighted_node = node;
-                lister->raw_item_index = node->raw_index;
-            }
             counter += 1;
         }
     }
+    
+    lister_update_selection_values(lister);
 }
 
 function void
@@ -474,8 +519,8 @@ lister_run(Application_Links *app, View_ID view, Lister *lister){
                     
                     case KeyCode_Up:
                     {
-                        if (lister->handlers.navigate_up != 0){
-                            lister->handlers.navigate_up(app);
+                        if (lister->handlers.navigate != 0){
+                            lister->handlers.navigate(app, view, lister, -1);
                         }
                         else{
                             handled = false;
@@ -484,8 +529,30 @@ lister_run(Application_Links *app, View_ID view, Lister *lister){
                     
                     case KeyCode_Down:
                     {
-                        if (lister->handlers.navigate_down != 0){
-                            lister->handlers.navigate_down(app);
+                        if (lister->handlers.navigate != 0){
+                            lister->handlers.navigate(app, view, lister, 1);
+                        }
+                        else{
+                            handled = false;
+                        }
+                    }break;
+                    
+                    case KeyCode_PageUp:
+                    {
+                        if (lister->handlers.navigate != 0){
+                            lister->handlers.navigate(app, view, lister,
+                                                      -lister->visible_count);
+                        }
+                        else{
+                            handled = false;
+                        }
+                    }break;
+                    
+                    case KeyCode_PageDown:
+                    {
+                        if (lister->handlers.navigate != 0){
+                            lister->handlers.navigate(app, view, lister,
+                                                      lister->visible_count);
                         }
                         else{
                             handled = false;
@@ -645,5 +712,53 @@ lister_add_item(Lister *lister, String_Const_u8 string, String_Const_u8 status,
                            user_data, extra_space));
 }
 
+function void
+lister__write_string__default(Application_Links *app){
+    View_ID view = get_active_view(app, AccessAll);
+    Lister *lister = view_get_lister(view);
+    if (lister != 0){
+        User_Input in = get_current_input(app);
+        String_Const_u8 string = to_writable(&in);
+        if (string.str != 0 && string.size > 0){
+            lister_append_text_field(lister, string);
+            lister_append_key(lister, string);
+            lister->item_index = 0;
+            lister_zero_scroll(lister);
+            lister_update_filtered_list(app, view, lister);
+        }
+    }
+}
+
+function void
+lister__backspace_text_field__default(Application_Links *app){
+    View_ID view = get_active_view(app, AccessAll);
+    Lister *lister = view_get_lister(view);
+    if (lister != 0){
+        lister->text_field.string = backspace_utf8(lister->text_field.string);
+        lister->key_string.string = backspace_utf8(lister->key_string.string);
+        lister->item_index = 0;
+        lister_zero_scroll(lister);
+        lister_update_filtered_list(app, view, lister);
+    }
+}
+
+function void
+lister__navigate__default(Application_Links *app, View_ID view, Lister *lister,
+                          i32 delta){
+    i32 new_index = lister->item_index + delta;
+    if (new_index < 0 && lister->item_index == 0){
+        lister->item_index = lister->filtered.count - 1;
+    }
+    else if (new_index >= lister->filtered.count &&
+             lister->item_index == lister->filtered.count - 1){
+        lister->item_index = 0;
+    }
+    else{
+        lister->item_index = clamp(0, new_index, lister->filtered.count - 1);
+    }
+    lister->set_vertical_focus_to_item = true;
+    lister_update_selection_values(lister);
+}
+
 // BOTTOM
 
diff --git a/custom/4coder_lister_base.h b/custom/4coder_lister_base.h
index 7e7524dc..3ead6dab 100644
--- a/custom/4coder_lister_base.h
+++ b/custom/4coder_lister_base.h
@@ -44,14 +44,16 @@ struct Lister_Node_Ptr_Array{
 };
 
 typedef Lister_Activation_Code Lister_Key_Stroke_Function(Application_Links *app);
+typedef void Lister_Navigate_Function(Application_Links *app,
+                                      View_ID view, struct Lister *lister,
+                                      i32 index_delta);
 
 struct Lister_Handlers{
     Lister_Activation_Type *activate;
     Lister_Regenerate_List_Function_Type *refresh;
     Custom_Command_Function *write_character;
     Custom_Command_Function *backspace;
-    Custom_Command_Function *navigate_up;
-    Custom_Command_Function *navigate_down;
+    Lister_Navigate_Function *navigate;
     Lister_Key_Stroke_Function *key_stroke;
 };
 
@@ -78,13 +80,14 @@ struct Lister{
     Temp_Memory filter_restore_point;
     Lister_Node_Ptr_Array filtered;
     
-    b32 set_view_vertical_focus_to_item;
+    b32 set_vertical_focus_to_item;
     Lister_Node *highlighted_node;
     void *hot_user_data;
     i32 item_index;
     i32 raw_item_index;
     
     Basic_Scroll scroll;
+    i32 visible_count;
 };
 
 struct Lister_Prealloced_String{
diff --git a/custom/4coder_lists.cpp b/custom/4coder_lists.cpp
index 9349598c..ff7c97b0 100644
--- a/custom/4coder_lists.cpp
+++ b/custom/4coder_lists.cpp
@@ -5,64 +5,6 @@ such as open file, switch buffer, or kill buffer.
 
 // TOP
 
-function void
-lister__write_string__default(Application_Links *app){
-    View_ID view = get_active_view(app, AccessAll);
-    Lister *lister = view_get_lister(view);
-    if (lister != 0){
-        User_Input in = get_current_input(app);
-        String_Const_u8 string = to_writable(&in);
-        if (string.str != 0 && string.size > 0){
-            lister_append_text_field(lister, string);
-            lister_append_key(lister, string);
-            lister->item_index = 0;
-            view_zero_scroll(app, view);
-            lister_update_filtered_list(app, view, lister);
-        }
-    }
-}
-
-function void
-lister__backspace_text_field__default(Application_Links *app){
-    View_ID view = get_active_view(app, AccessAll);
-    Lister *lister = view_get_lister(view);
-    if (lister != 0){
-        lister->text_field.string = backspace_utf8(lister->text_field.string);
-        lister->key_string.string = backspace_utf8(lister->key_string.string);
-        lister->item_index = 0;
-        view_zero_scroll(app, view);
-        lister_update_filtered_list(app, view, lister);
-    }
-}
-
-function void
-lister__move_up__default(Application_Links *app){
-    View_ID view = get_active_view(app, AccessAll);
-    Lister *lister = view_get_lister(view);
-    if (lister != 0){
-        lister->item_index = lister->item_index - 1;
-        if (lister->item_index < 0){
-            lister->item_index = lister->filtered.count - 1;
-        }
-        lister->set_view_vertical_focus_to_item = true;
-        lister_update_filtered_list(app, view, lister);
-    }
-}
-
-function void
-lister__move_down__default(Application_Links *app){
-    View_ID view = get_active_view(app, AccessAll);
-    Lister *lister = view_get_lister(view);
-    if (lister != 0){
-        lister->item_index = lister->item_index + 1;
-        if (lister->item_index > lister->filtered.count - 1){
-            lister->item_index = 0;
-        }
-        lister->set_view_vertical_focus_to_item = true;
-        lister_update_filtered_list(app, view, lister);
-    }
-}
-
 function void
 lister__write_character__file_path(Application_Links *app){
     View_ID view = get_active_view(app, AccessAll);
@@ -80,7 +22,7 @@ lister__write_character__file_path(Application_Links *app){
                 lister_call_refresh_handler(app, view, lister);
             }
             lister->item_index = 0;
-            view_zero_scroll(app, view);
+            lister_zero_scroll(lister);
             lister_update_filtered_list(app, view, lister);
         }
     }
@@ -117,7 +59,7 @@ lister__backspace_text_field__file_path(Application_Links *app){
             }
             
             lister->item_index = 0;
-            view_zero_scroll(app, view);
+            lister_zero_scroll(lister);
             lister_update_filtered_list(app, view, lister);
         }
     }
@@ -158,16 +100,14 @@ lister_get_default_handlers(void){
     Lister_Handlers handlers = {};
     handlers.write_character = lister__write_string__default;
     handlers.backspace       = lister__backspace_text_field__default;
-    handlers.navigate_up     = lister__move_up__default;
-    handlers.navigate_down   = lister__move_down__default;
+    handlers.navigate        = lister__navigate__default;
     return(handlers);
 }
 
 function Lister_Handlers
 lister_get_fixed_list_handlers(void){
     Lister_Handlers handlers = {};
-    handlers.navigate_up     = lister__move_up__default;
-    handlers.navigate_down   = lister__move_down__default;
+    handlers.navigate        = lister__navigate__default;
     handlers.key_stroke      = lister__key_stroke__fixed_list;
     return(handlers);
 }
@@ -197,8 +137,6 @@ run_lister_with_refresh_handler(Application_Links *app, char *query_string,
     }
 }
 
-global_const i32 default_string_size_estimation = 0;
-
 function i32
 lister__get_arena_size_(i32 option_count, i32 user_data_size,
                         i32 estimated_string_space_size){
@@ -230,7 +168,6 @@ run_lister_with_fixed_options(Application_Links *app, char *query_string,
                               Lister_Handlers handlers,
                               void *user_data, i32 user_data_size,
                               Lister_Fixed_Option *options, i32 option_count,
-                              i32 estimated_string_space_size,
                               View_ID view){
     Scratch_Block scratch(app);
     Lister *lister = begin_lister(app, scratch, view, user_data, user_data_size);
@@ -252,14 +189,12 @@ run_lister_with_fixed_options(Application_Links *app, char *query_string,
                               Lister_Activation_Type *activate,
                               void *user_data, i32 user_data_size,
                               Lister_Fixed_Option *options, i32 option_count,
-                              i32 estimated_string_space_size,
                               View_ID view){
     Lister_Handlers handlers = lister_get_fixed_list_handlers();
     handlers.activate = activate;
     run_lister_with_fixed_options(app, query_string,
                                   handlers, user_data, user_data_size,
                                   options, option_count,
-                                  estimated_string_space_size,
                                   view);
 }
 
@@ -486,7 +421,7 @@ do_gui_sure_to_kill(Application_Links *app, Buffer_ID buffer, View_ID view){
     data.id = buffer;
     run_lister_with_fixed_options(app, "There are unsaved changes, close anyway?",
                                   activate_confirm_kill, &data, sizeof(data),
-                                  options, option_count, default_string_size_estimation,
+                                  options, option_count,
                                   view);
     return(data.do_kill);
 }
@@ -530,7 +465,7 @@ do_gui_sure_to_close_4coder(Application_Links *app, View_ID view){
     run_lister_with_fixed_options(app, "There are one or more buffers with unsave changes, close anyway?",
                                   activate_confirm_close_4coder,
                                   &do_exit, sizeof(do_exit),
-                                  options, option_count, default_string_size_estimation,
+                                  options, option_count,
                                   view);
     return(do_exit);
 }
diff --git a/custom/4coder_types.h b/custom/4coder_types.h
index 663ce09c..c3bb2145 100644
--- a/custom/4coder_types.h
+++ b/custom/4coder_types.h
@@ -253,6 +253,12 @@ STRUCT Buffer_Identifier{
     Buffer_ID id;
 };
 
+typedef i32 Set_Buffer_Scroll_Rule;
+enum{
+    SetBufferScroll_NoCursorChange,
+    SetBufferScroll_SnapCursorIntoView,
+};
+
 struct Buffer_Scroll{
     Buffer_Point position;
     Buffer_Point target;
@@ -476,8 +482,8 @@ STRUCT User_Input{
 typedef i32 Hook_ID;
 enum{
     HookID_RenderCaller,
+    HookID_DeltaRule,
     HookID_BufferViewerUpdate,
-    HookID_ScrollRule,
     HookID_ViewEventHandler,
     HookID_BufferNameResolver,
     HookID_BeginBuffer,
@@ -512,9 +518,9 @@ typedef i32 Buffer_Edit_Range_Function(Application_Links *app, Buffer_ID buffer_
 #define BUFFER_EDIT_RANGE_SIG(name) i32 name(Application_Links *app, Buffer_ID buffer_id,\
 Interval_i64 range, String_Const_u8 text)
 
-typedef Vec2_f32 Delta_Rule_Function(Vec2_f32 pending_delta, View_ID view_id, b32 is_new_target, f32 dt);
+typedef Vec2_f32 Delta_Rule_Function(Vec2_f32 pending, b32 is_new_target, f32 dt, void *data);
 #define DELTA_RULE_SIG(name) \
-Vec2_f32 name(Vec2_f32 pending_delta, View_ID view_id, b32 is_new_target, f32 dt)
+Vec2_f32 name(Vec2_f32 pending, b32 is_new_target, f32 dt, void *data)
 
 typedef Rect_f32 Buffer_Region_Function(Application_Links *app, View_ID view_id, Rect_f32 region);
 
@@ -532,6 +538,8 @@ typedef void Render_Caller_Function(Application_Links *app, Frame_Info frame_inf
 
 struct View_Context{
     Render_Caller_Function *render_caller;
+    Delta_Rule_Function *delta_rule;
+    umem delta_rule_memory_size;
     b32 hides_buffer;
 };
 
diff --git a/custom/generated/command_metadata.h b/custom/generated/command_metadata.h
index bb235c3b..73b3a39d 100644
--- a/custom/generated/command_metadata.h
+++ b/custom/generated/command_metadata.h
@@ -227,12 +227,12 @@ i32 line_number;
 };
 static Command_Metadata fcoder_metacmd_table[205] = {
 { PROC_LINKS(default_view_input_handler, 0), "default_view_input_handler", 26,  "Input consumption loop for default view behavior", 48, "w:\\4ed\\code\\custom\\4coder_default_hooks.cpp", 43, 56 },
-{ PROC_LINKS(seek_beginning_of_textual_line, 0), "seek_beginning_of_textual_line", 30,  "Seeks the cursor to the beginning of the line across all text.", 62, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 1979 },
-{ PROC_LINKS(seek_end_of_textual_line, 0), "seek_end_of_textual_line", 24,  "Seeks the cursor to the end of the line across all text.", 56, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 1985 },
-{ PROC_LINKS(seek_beginning_of_line, 0), "seek_beginning_of_line", 22,  "Seeks the cursor to the beginning of the visual line.", 53, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 1991 },
-{ PROC_LINKS(seek_end_of_line, 0), "seek_end_of_line", 16,  "Seeks the cursor to the end of the visual line.", 47, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 1997 },
-{ PROC_LINKS(goto_beginning_of_file, 0), "goto_beginning_of_file", 22,  "Sets the cursor to the beginning of the file.", 45, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2003 },
-{ PROC_LINKS(goto_end_of_file, 0), "goto_end_of_file", 16,  "Sets the cursor to the end of the file.", 39, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2011 },
+{ PROC_LINKS(seek_beginning_of_textual_line, 0), "seek_beginning_of_textual_line", 30,  "Seeks the cursor to the beginning of the line across all text.", 62, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 1996 },
+{ PROC_LINKS(seek_end_of_textual_line, 0), "seek_end_of_textual_line", 24,  "Seeks the cursor to the end of the line across all text.", 56, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2002 },
+{ PROC_LINKS(seek_beginning_of_line, 0), "seek_beginning_of_line", 22,  "Seeks the cursor to the beginning of the visual line.", 53, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2008 },
+{ PROC_LINKS(seek_end_of_line, 0), "seek_end_of_line", 16,  "Seeks the cursor to the end of the visual line.", 47, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2014 },
+{ PROC_LINKS(goto_beginning_of_file, 0), "goto_beginning_of_file", 22,  "Sets the cursor to the beginning of the file.", 45, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2020 },
+{ PROC_LINKS(goto_end_of_file, 0), "goto_end_of_file", 16,  "Sets the cursor to the end of the file.", 39, "w:\\4ed\\code\\custom\\4coder_helper.cpp", 36, 2028 },
 { PROC_LINKS(change_active_panel, 0), "change_active_panel", 19,  "Change the currently active panel, moving to the panel with the next highest view_id.", 85, "w:\\4ed\\code\\custom\\4coder_default_framework.cpp", 47, 196 },
 { PROC_LINKS(change_active_panel_backwards, 0), "change_active_panel_backwards", 29,  "Change the currently active panel, moving to the panel with the next lowest view_id.", 84, "w:\\4ed\\code\\custom\\4coder_default_framework.cpp", 47, 206 },
 { PROC_LINKS(open_panel_vsplit, 0), "open_panel_vsplit", 17,  "Create a new panel by vertically splitting the active panel.", 60, "w:\\4ed\\code\\custom\\4coder_default_framework.cpp", 47, 216 },
@@ -344,12 +344,12 @@ static Command_Metadata fcoder_metacmd_table[205] = {
 { PROC_LINKS(redo_all_buffers, 0), "redo_all_buffers", 16,  "Advances forward through the undo history in the buffer containing the most recent regular edit.", 96, "w:\\4ed\\code\\custom\\4coder_base_commands.cpp", 43, 1939 },
 { PROC_LINKS(open_in_other, 0), "open_in_other", 13,  "Interactively opens a file in the other panel.", 46, "w:\\4ed\\code\\custom\\4coder_base_commands.cpp", 43, 2040 },
 { PROC_LINKS(default_file_externally_modified, 0), "default_file_externally_modified", 32,  "Notes the external modification of attached files by printing a message.", 72, "w:\\4ed\\code\\custom\\4coder_base_commands.cpp", 43, 2047 },
-{ PROC_LINKS(interactive_switch_buffer, 0), "interactive_switch_buffer", 25,  "Interactively switch to an open buffer.", 39, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 552 },
-{ PROC_LINKS(interactive_kill_buffer, 0), "interactive_kill_buffer", 23,  "Interactively kill an open buffer.", 34, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 571 },
-{ PROC_LINKS(interactive_open_or_new, 0), "interactive_open_or_new", 23,  "Interactively open a file out of the file system.", 49, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 642 },
-{ PROC_LINKS(interactive_new, 0), "interactive_new", 15,  "Interactively creates a new file.", 33, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 681 },
-{ PROC_LINKS(interactive_open, 0), "interactive_open", 16,  "Interactively opens a file.", 27, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 714 },
-{ PROC_LINKS(command_lister, 0), "command_lister", 14,  "Opens an interactive list of all registered commands.", 53, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 774 },
+{ PROC_LINKS(interactive_switch_buffer, 0), "interactive_switch_buffer", 25,  "Interactively switch to an open buffer.", 39, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 487 },
+{ PROC_LINKS(interactive_kill_buffer, 0), "interactive_kill_buffer", 23,  "Interactively kill an open buffer.", 34, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 506 },
+{ PROC_LINKS(interactive_open_or_new, 0), "interactive_open_or_new", 23,  "Interactively open a file out of the file system.", 49, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 577 },
+{ PROC_LINKS(interactive_new, 0), "interactive_new", 15,  "Interactively creates a new file.", 33, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 616 },
+{ PROC_LINKS(interactive_open, 0), "interactive_open", 16,  "Interactively opens a file.", 27, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 649 },
+{ PROC_LINKS(command_lister, 0), "command_lister", 14,  "Opens an interactive list of all registered commands.", 53, "w:\\4ed\\code\\custom\\4coder_lists.cpp", 35, 709 },
 { PROC_LINKS(auto_indent_whole_file, 0), "auto_indent_whole_file", 22,  "Audo-indents the entire current buffer.", 39, "w:\\4ed\\code\\custom\\4coder_auto_indent.cpp", 41, 356 },
 { PROC_LINKS(auto_indent_line_at_cursor, 0), "auto_indent_line_at_cursor", 26,  "Auto-indents the line on which the cursor sits.", 47, "w:\\4ed\\code\\custom\\4coder_auto_indent.cpp", 41, 365 },
 { PROC_LINKS(auto_indent_range, 0), "auto_indent_range", 17,  "Auto-indents the range between the cursor and the mark.", 55, "w:\\4ed\\code\\custom\\4coder_auto_indent.cpp", 41, 375 },
diff --git a/custom/generated/custom_api.cpp b/custom/generated/custom_api.cpp
index 14d90ba4..353d1f6d 100644
--- a/custom/generated/custom_api.cpp
+++ b/custom/generated/custom_api.cpp
@@ -91,6 +91,7 @@ vtable->view_post_fade = view_post_fade;
 vtable->view_push_context = view_push_context;
 vtable->view_pop_context = view_pop_context;
 vtable->view_current_context = view_current_context;
+vtable->view_current_context_hook_memory = view_current_context_hook_memory;
 vtable->create_user_managed_scope = create_user_managed_scope;
 vtable->destroy_user_managed_scope = destroy_user_managed_scope;
 vtable->get_global_managed_scope = get_global_managed_scope;
@@ -117,6 +118,7 @@ vtable->get_current_input = get_current_input;
 vtable->set_current_input = set_current_input;
 vtable->leave_current_input_unhandled = leave_current_input_unhandled;
 vtable->set_custom_hook = set_custom_hook;
+vtable->set_custom_hook_memory_size = set_custom_hook_memory_size;
 vtable->get_mouse_state = get_mouse_state;
 vtable->get_active_query_bars = get_active_query_bars;
 vtable->start_query_bar = start_query_bar;
@@ -263,6 +265,7 @@ view_post_fade = vtable->view_post_fade;
 view_push_context = vtable->view_push_context;
 view_pop_context = vtable->view_pop_context;
 view_current_context = vtable->view_current_context;
+view_current_context_hook_memory = vtable->view_current_context_hook_memory;
 create_user_managed_scope = vtable->create_user_managed_scope;
 destroy_user_managed_scope = vtable->destroy_user_managed_scope;
 get_global_managed_scope = vtable->get_global_managed_scope;
@@ -289,6 +292,7 @@ get_current_input = vtable->get_current_input;
 set_current_input = vtable->set_current_input;
 leave_current_input_unhandled = vtable->leave_current_input_unhandled;
 set_custom_hook = vtable->set_custom_hook;
+set_custom_hook_memory_size = vtable->set_custom_hook_memory_size;
 get_mouse_state = vtable->get_mouse_state;
 get_active_query_bars = vtable->get_active_query_bars;
 start_query_bar = vtable->start_query_bar;
diff --git a/custom/generated/custom_api.h b/custom/generated/custom_api.h
index 5ce998cc..f5b35b46 100644
--- a/custom/generated/custom_api.h
+++ b/custom/generated/custom_api.h
@@ -82,13 +82,14 @@
 #define custom_buffer_compute_cursor_sig() Buffer_Cursor custom_buffer_compute_cursor(Application_Links* app, Buffer_ID buffer, Buffer_Seek seek)
 #define custom_view_compute_cursor_sig() Buffer_Cursor custom_view_compute_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek)
 #define custom_view_set_cursor_sig() b32 custom_view_set_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek)
-#define custom_view_set_buffer_scroll_sig() b32 custom_view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll)
+#define custom_view_set_buffer_scroll_sig() b32 custom_view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll, Set_Buffer_Scroll_Rule rule)
 #define custom_view_set_mark_sig() b32 custom_view_set_mark(Application_Links* app, View_ID view_id, Buffer_Seek seek)
 #define custom_view_set_buffer_sig() b32 custom_view_set_buffer(Application_Links* app, View_ID view_id, Buffer_ID buffer_id, Set_Buffer_Flag flags)
 #define custom_view_post_fade_sig() b32 custom_view_post_fade(Application_Links* app, View_ID view_id, f32 seconds, Range_i64 range, int_color color)
 #define custom_view_push_context_sig() b32 custom_view_push_context(Application_Links* app, View_ID view_id, View_Context* ctx)
 #define custom_view_pop_context_sig() b32 custom_view_pop_context(Application_Links* app, View_ID view_id)
 #define custom_view_current_context_sig() View_Context custom_view_current_context(Application_Links* app, View_ID view_id)
+#define custom_view_current_context_hook_memory_sig() Data custom_view_current_context_hook_memory(Application_Links* app, View_ID view_id, Hook_ID hook_id)
 #define custom_create_user_managed_scope_sig() Managed_Scope custom_create_user_managed_scope(Application_Links* app)
 #define custom_destroy_user_managed_scope_sig() b32 custom_destroy_user_managed_scope(Application_Links* app, Managed_Scope scope)
 #define custom_get_global_managed_scope_sig() Managed_Scope custom_get_global_managed_scope(Application_Links* app)
@@ -115,6 +116,7 @@
 #define custom_set_current_input_sig() void custom_set_current_input(Application_Links* app, User_Input* input)
 #define custom_leave_current_input_unhandled_sig() void custom_leave_current_input_unhandled(Application_Links* app)
 #define custom_set_custom_hook_sig() void custom_set_custom_hook(Application_Links* app, Hook_ID hook_id, Void_Func* func_ptr)
+#define custom_set_custom_hook_memory_size_sig() b32 custom_set_custom_hook_memory_size(Application_Links* app, Hook_ID hook_id, umem size)
 #define custom_get_mouse_state_sig() Mouse_State custom_get_mouse_state(Application_Links* app)
 #define custom_get_active_query_bars_sig() b32 custom_get_active_query_bars(Application_Links* app, View_ID view_id, i32 max_result_count, Query_Bar_Ptr_Array* array_out)
 #define custom_start_query_bar_sig() b32 custom_start_query_bar(Application_Links* app, Query_Bar* bar, u32 flags)
@@ -250,13 +252,14 @@ typedef Managed_Scope custom_view_get_managed_scope_type(Application_Links* app,
 typedef Buffer_Cursor custom_buffer_compute_cursor_type(Application_Links* app, Buffer_ID buffer, Buffer_Seek seek);
 typedef Buffer_Cursor custom_view_compute_cursor_type(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 typedef b32 custom_view_set_cursor_type(Application_Links* app, View_ID view_id, Buffer_Seek seek);
-typedef b32 custom_view_set_buffer_scroll_type(Application_Links* app, View_ID view_id, Buffer_Scroll scroll);
+typedef b32 custom_view_set_buffer_scroll_type(Application_Links* app, View_ID view_id, Buffer_Scroll scroll, Set_Buffer_Scroll_Rule rule);
 typedef b32 custom_view_set_mark_type(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 typedef b32 custom_view_set_buffer_type(Application_Links* app, View_ID view_id, Buffer_ID buffer_id, Set_Buffer_Flag flags);
 typedef b32 custom_view_post_fade_type(Application_Links* app, View_ID view_id, f32 seconds, Range_i64 range, int_color color);
 typedef b32 custom_view_push_context_type(Application_Links* app, View_ID view_id, View_Context* ctx);
 typedef b32 custom_view_pop_context_type(Application_Links* app, View_ID view_id);
 typedef View_Context custom_view_current_context_type(Application_Links* app, View_ID view_id);
+typedef Data custom_view_current_context_hook_memory_type(Application_Links* app, View_ID view_id, Hook_ID hook_id);
 typedef Managed_Scope custom_create_user_managed_scope_type(Application_Links* app);
 typedef b32 custom_destroy_user_managed_scope_type(Application_Links* app, Managed_Scope scope);
 typedef Managed_Scope custom_get_global_managed_scope_type(Application_Links* app);
@@ -283,6 +286,7 @@ typedef User_Input custom_get_current_input_type(Application_Links* app);
 typedef void custom_set_current_input_type(Application_Links* app, User_Input* input);
 typedef void custom_leave_current_input_unhandled_type(Application_Links* app);
 typedef void custom_set_custom_hook_type(Application_Links* app, Hook_ID hook_id, Void_Func* func_ptr);
+typedef b32 custom_set_custom_hook_memory_size_type(Application_Links* app, Hook_ID hook_id, umem size);
 typedef Mouse_State custom_get_mouse_state_type(Application_Links* app);
 typedef b32 custom_get_active_query_bars_type(Application_Links* app, View_ID view_id, i32 max_result_count, Query_Bar_Ptr_Array* array_out);
 typedef b32 custom_start_query_bar_type(Application_Links* app, Query_Bar* bar, u32 flags);
@@ -426,6 +430,7 @@ custom_view_post_fade_type *view_post_fade;
 custom_view_push_context_type *view_push_context;
 custom_view_pop_context_type *view_pop_context;
 custom_view_current_context_type *view_current_context;
+custom_view_current_context_hook_memory_type *view_current_context_hook_memory;
 custom_create_user_managed_scope_type *create_user_managed_scope;
 custom_destroy_user_managed_scope_type *destroy_user_managed_scope;
 custom_get_global_managed_scope_type *get_global_managed_scope;
@@ -452,6 +457,7 @@ custom_get_current_input_type *get_current_input;
 custom_set_current_input_type *set_current_input;
 custom_leave_current_input_unhandled_type *leave_current_input_unhandled;
 custom_set_custom_hook_type *set_custom_hook;
+custom_set_custom_hook_memory_size_type *set_custom_hook_memory_size;
 custom_get_mouse_state_type *get_mouse_state;
 custom_get_active_query_bars_type *get_active_query_bars;
 custom_start_query_bar_type *start_query_bar;
@@ -589,13 +595,14 @@ internal Managed_Scope view_get_managed_scope(Application_Links* app, View_ID vi
 internal Buffer_Cursor buffer_compute_cursor(Application_Links* app, Buffer_ID buffer, Buffer_Seek seek);
 internal Buffer_Cursor view_compute_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 internal b32 view_set_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek);
-internal b32 view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll);
+internal b32 view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll, Set_Buffer_Scroll_Rule rule);
 internal b32 view_set_mark(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 internal b32 view_set_buffer(Application_Links* app, View_ID view_id, Buffer_ID buffer_id, Set_Buffer_Flag flags);
 internal b32 view_post_fade(Application_Links* app, View_ID view_id, f32 seconds, Range_i64 range, int_color color);
 internal b32 view_push_context(Application_Links* app, View_ID view_id, View_Context* ctx);
 internal b32 view_pop_context(Application_Links* app, View_ID view_id);
 internal View_Context view_current_context(Application_Links* app, View_ID view_id);
+internal Data view_current_context_hook_memory(Application_Links* app, View_ID view_id, Hook_ID hook_id);
 internal Managed_Scope create_user_managed_scope(Application_Links* app);
 internal b32 destroy_user_managed_scope(Application_Links* app, Managed_Scope scope);
 internal Managed_Scope get_global_managed_scope(Application_Links* app);
@@ -622,6 +629,7 @@ internal User_Input get_current_input(Application_Links* app);
 internal void set_current_input(Application_Links* app, User_Input* input);
 internal void leave_current_input_unhandled(Application_Links* app);
 internal void set_custom_hook(Application_Links* app, Hook_ID hook_id, Void_Func* func_ptr);
+internal b32 set_custom_hook_memory_size(Application_Links* app, Hook_ID hook_id, umem size);
 internal Mouse_State get_mouse_state(Application_Links* app);
 internal b32 get_active_query_bars(Application_Links* app, View_ID view_id, i32 max_result_count, Query_Bar_Ptr_Array* array_out);
 internal b32 start_query_bar(Application_Links* app, Query_Bar* bar, u32 flags);
@@ -766,6 +774,7 @@ global custom_view_post_fade_type *view_post_fade = 0;
 global custom_view_push_context_type *view_push_context = 0;
 global custom_view_pop_context_type *view_pop_context = 0;
 global custom_view_current_context_type *view_current_context = 0;
+global custom_view_current_context_hook_memory_type *view_current_context_hook_memory = 0;
 global custom_create_user_managed_scope_type *create_user_managed_scope = 0;
 global custom_destroy_user_managed_scope_type *destroy_user_managed_scope = 0;
 global custom_get_global_managed_scope_type *get_global_managed_scope = 0;
@@ -792,6 +801,7 @@ global custom_get_current_input_type *get_current_input = 0;
 global custom_set_current_input_type *set_current_input = 0;
 global custom_leave_current_input_unhandled_type *leave_current_input_unhandled = 0;
 global custom_set_custom_hook_type *set_custom_hook = 0;
+global custom_set_custom_hook_memory_size_type *set_custom_hook_memory_size = 0;
 global custom_get_mouse_state_type *get_mouse_state = 0;
 global custom_get_active_query_bars_type *get_active_query_bars = 0;
 global custom_start_query_bar_type *start_query_bar = 0;
diff --git a/custom/generated/custom_api_master_list.h b/custom/generated/custom_api_master_list.h
index 1f6eee70..8a7c906d 100644
--- a/custom/generated/custom_api_master_list.h
+++ b/custom/generated/custom_api_master_list.h
@@ -82,13 +82,14 @@ api(custom) function Managed_Scope view_get_managed_scope(Application_Links* app
 api(custom) function Buffer_Cursor buffer_compute_cursor(Application_Links* app, Buffer_ID buffer, Buffer_Seek seek);
 api(custom) function Buffer_Cursor view_compute_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 api(custom) function b32 view_set_cursor(Application_Links* app, View_ID view_id, Buffer_Seek seek);
-api(custom) function b32 view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll);
+api(custom) function b32 view_set_buffer_scroll(Application_Links* app, View_ID view_id, Buffer_Scroll scroll, Set_Buffer_Scroll_Rule rule);
 api(custom) function b32 view_set_mark(Application_Links* app, View_ID view_id, Buffer_Seek seek);
 api(custom) function b32 view_set_buffer(Application_Links* app, View_ID view_id, Buffer_ID buffer_id, Set_Buffer_Flag flags);
 api(custom) function b32 view_post_fade(Application_Links* app, View_ID view_id, f32 seconds, Range_i64 range, int_color color);
 api(custom) function b32 view_push_context(Application_Links* app, View_ID view_id, View_Context* ctx);
 api(custom) function b32 view_pop_context(Application_Links* app, View_ID view_id);
 api(custom) function View_Context view_current_context(Application_Links* app, View_ID view_id);
+api(custom) function Data view_current_context_hook_memory(Application_Links* app, View_ID view_id, Hook_ID hook_id);
 api(custom) function Managed_Scope create_user_managed_scope(Application_Links* app);
 api(custom) function b32 destroy_user_managed_scope(Application_Links* app, Managed_Scope scope);
 api(custom) function Managed_Scope get_global_managed_scope(Application_Links* app);
@@ -115,6 +116,7 @@ api(custom) function User_Input get_current_input(Application_Links* app);
 api(custom) function void set_current_input(Application_Links* app, User_Input* input);
 api(custom) function void leave_current_input_unhandled(Application_Links* app);
 api(custom) function void set_custom_hook(Application_Links* app, Hook_ID hook_id, Void_Func* func_ptr);
+api(custom) function b32 set_custom_hook_memory_size(Application_Links* app, Hook_ID hook_id, umem size);
 api(custom) function Mouse_State get_mouse_state(Application_Links* app);
 api(custom) function b32 get_active_query_bars(Application_Links* app, View_ID view_id, i32 max_result_count, Query_Bar_Ptr_Array* array_out);
 api(custom) function b32 start_query_bar(Application_Links* app, Query_Bar* bar, u32 flags);