diff --git a/client/include/ui.h b/client/include/ui.h
index d02efdf..e8a4388 100644
--- a/client/include/ui.h
+++ b/client/include/ui.h
@@ -145,6 +145,19 @@ typedef struct GPUContainerStruct {
   VkDeviceAddress context;
 } GPUContainer;
 
+typedef void (*ui_key_callback)(void* ptr, int key, int action, int mods);
+typedef void (*ui_button_callback)(void* ptr, float x, float y, int button, int action, int mods);
+typedef void (*ui_scroll_callback)(void* ptr, double x, double y);
+typedef void (*ui_cursor_callback)(void* ptr, float x, float y);
+
+typedef struct UICallbacksStruct {
+  uint32_t           element;
+  ui_key_callback    key;
+  ui_button_callback button;
+  ui_scroll_callback scroll;
+  ui_cursor_callback cursor;
+} UICallbacks;
+
 typedef struct ContainerStruct {
   VkBuffer container[MAX_FRAMES_IN_FLIGHT];
 
@@ -157,6 +170,9 @@ typedef struct ContainerStruct {
   uint32_t id;
   uint32_t layer_count;
   Layer* layers;
+
+  uint32_t callback_count;
+  UICallbacks* callbacks;
 } Container;
 
 typedef struct ContainerInputStruct {
@@ -167,6 +183,9 @@ typedef struct ContainerInputStruct {
 
   uint32_t layer_count;
   LayerInput* layers;
+
+  uint32_t callback_count;
+  UICallbacks* callbacks;
 } ContainerInput;
 
 typedef struct GPUUIContextStruct {
@@ -176,7 +195,7 @@ typedef struct GPUUIContextStruct {
   vec2 scale;
 } GPUUIContext;
 
-typedef struct UIContext {
+typedef struct UIContextStruct {
   VkDeviceAddress address;
 
   VkBuffer context;
@@ -211,9 +230,11 @@ typedef struct UIContext {
 
   FT_Library freetype;
 
-  uint32_t active_element;
-  uint32_t active_container;
-  uint32_t active_captures;
+  UICallbacks* active_callbacks;
+  uint32_t     active_container;
+  uint32_t     active_element;
+
+  double cursor[2];
 } UIContext;
 
 VkResult create_ui_context(
@@ -267,6 +288,9 @@ VkResult update_ui_string(
     UIContext* ui,
     RenderContext* gpu);
 
+Container* context_container(uint32_t container_id, UIContext* ui);
+GPUDrawable* container_drawable(uint32_t element_id, Container* container);
+
 bool ui_intersect(
     double cursor[2],
     RenderContext* gpu,
@@ -275,4 +299,10 @@ bool ui_intersect(
     uint32_t* element,
     vec2 position); 
 
+void set_active_element(uint32_t container, uint32_t element, UIContext* ui);
+
+void clear_active_element(UIContext* ui);
+
+void anchor_offset(RenderContext* gpu, Container* container, vec2 offset);
+
 #endif