diff --git a/include/button.h b/include/button.h
deleted file mode 100644
index b654ab9..0000000
--- a/include/button.h
+++ /dev/null
@@ -1,16 +0,0 @@
-#ifndef BUTTON_H
-#define BUTTON_H
-
-#include "window.h"
-
-#define BUTTON_WIDTH 100
-#define BUTTON_HEIGHT 40
-
-typedef struct button button_t;
-struct button {
-  rect_t rect;
-};
-
-void draw_button(const window_t *wnd, const button_t *button);
-
-#endif // !BUTTON_H
diff --git a/include/nodes.h b/include/nodes.h
index 00a4685..b07a592 100644
--- a/include/nodes.h
+++ b/include/nodes.h
@@ -2,18 +2,11 @@
 #define NODES_H
 
 #include "aliases/aliases.h"
+#include "ui.h"
 #include "window.h"
 
 #define MAX_NODES 1024
 
-#define NODE_WIDTH 70
-#define NODE_HEIGHT 20
-
-#define IO_NODE_FILL_COLOUR ((colour_t){.abgr = 0xff2c84b7})
-#define IO_NODE_BORDER_COLOUR ((colour_t){.abgr = 0xff315c89})
-#define OP_NODE_FILL_COLOUR ((colour_t){.abgr = 0xffad6c3a})
-#define OP_NODE_BORDER_COLOUR ((colour_t){.abgr = 0xff8e4a33})
-
 typedef i32 (*node_func_t)(i32 a, i32 b);
 typedef enum node_type node_type_t;
 typedef union node_data node_data_t;
@@ -33,10 +26,9 @@ union node_data {
 
 struct node {
   rect_t rect;
+  ui_elem_colours_t colours;
   node_type_t type;
   node_data_t data;
 };
 
-void draw_node(const window_t *wnd, const node_t *node);
-
 #endif // !NODES_H
diff --git a/include/ui.h b/include/ui.h
index 6403253..7acbd55 100644
--- a/include/ui.h
+++ b/include/ui.h
@@ -1,10 +1,63 @@
 #ifndef UI_H
 #define UI_H
 
+#include "SDL_events.h"
 #include "aliases/aliases.h"
 #include "window.h"
 #include <stdbool.h>
 
-bool aabb(const rect_t *rect, i32 x, i32 y);
+#define MAX_UI_ELEMENTS 4096
+
+#define BUTTON_WIDTH 100
+#define BUTTON_HEIGHT 40
+
+#define NODE_WIDTH 70
+#define NODE_HEIGHT 20
+
+typedef enum ui_elem_type ui_elem_type_t;
+typedef struct ui_elem ui_elem_t;
+typedef struct ui_ctx ui_ctx_t;
+
+enum ui_elem_type {
+  UI_ELEM_NODE,
+  UI_ELEM_BUTTON,
+
+  COUNT_UI_ELEM,
+};
+
+struct ui_elem {
+  u64 id;
+  rect_t rect;
+  ui_elem_type_t type;
+};
+
+typedef struct ui_elem_colours ui_elem_colours_t;
+struct ui_elem_colours {
+  colour_t fill;
+  colour_t border;
+};
+
+struct ui_ctx {
+  u64 count;
+  i64 hovered;
+  i64 active;
+  i32 mouse_x;
+  i32 mouse_y;
+  i32 rel_x;
+  i32 rel_y;
+  bool mouse_down;
+  bool mouse_up;
+  const window_t *wnd;
+  ui_elem_t elements[MAX_UI_ELEMENTS];
+};
+
+void init_ui_ctx(ui_ctx_t *ctx);
+void reset_ui_ctx(ui_ctx_t *ctx);
+void handle_ui_events(const window_t *wnd, ui_ctx_t *ctx,
+                      const SDL_Event *event);
+bool button(const window_t *wnd, ui_ctx_t *ctx, rect_t rect,
+            ui_elem_colours_t colours);
+rect_t node(const window_t *wnd, ui_ctx_t *ctx, rect_t rect,
+            ui_elem_colours_t colours);
 
 #endif // !UI_H
diff --git a/include/window.h b/include/window.h
index 63ebb16..b1aadd1 100644
--- a/include/window.h
+++ b/include/window.h
@@ -63,7 +63,7 @@ void draw_point(const window_t *wnd, point_t p, colour_t colour);
 void draw_line(const window_t *wnd, const line_t *ln, colour_t colour);
 void draw_triangle(const window_t *wnd, const triangle_t *triangle,
                    colour_t colour);
-void draw_rect(const window_t *wnd, const rect_t *rect, colour_t colour);
-void fill_rect(const window_t *wnd, const rect_t *rect, colour_t colour);
+void draw_rect(const window_t *wnd, rect_t rect, colour_t colour);
+void fill_rect(const window_t *wnd, rect_t rect, colour_t colour);
 
 #endif // !WINDOW_H
diff --git a/src/button.c b/src/button.c
deleted file mode 100644
index fea3c07..0000000
--- a/src/button.c
+++ /dev/null
@@ -1,10 +0,0 @@
-#include "button.h"
-#include "window.h"
-
-#define BUTTON_FILL_COLOUR ((colour_t){.abgr = 0xff89a83c})
-#define BUTTON_BORDER_COLOUR ((colour_t){.abgr = 0xff768432})
-
-void draw_button(const window_t *wnd, const button_t *button) {
-  fill_rect(wnd, &(button->rect), BUTTON_FILL_COLOUR);
-  draw_rect(wnd, &(button->rect), BUTTON_BORDER_COLOUR);
-}
diff --git a/src/compositor.c b/src/compositor.c
index c508bf4..8324c2d 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -1,5 +1,4 @@
 #include "aliases/aliases.h"
-#include "button.h"
 #include "nodes.h"
 #include "ops.h"
 #include "ui.h"
@@ -19,23 +18,18 @@
 typedef struct compositor compositor_t;
 struct compositor {
   window_t windows[MAX_WINDOWS];
+  u32 active_window;
   SDL_Event event;
   bool running;
-  u64 mouse_x;
-  u64 mouse_y;
-  u64 last_clicked_mouse_x;
-  u64 last_clicked_mouse_y;
   i64 node_hovered;
   u64 count;
   node_t *nodes;
   bool move_node;
-  button_t buttons[COUNT_COMP_OPS];
-  i64 button_hovered;
-  i64 button_clicked;
+  ui_ctx_t ctx;
 };
 
 void add_node(compositor_t *comp, node_type_t type, node_data_t data, i32 x,
-              i32 y);
+              i32 y, ui_elem_colours_t colours);
 
 i32 run_main_loop(void) {
   if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
@@ -43,6 +37,9 @@ i32 run_main_loop(void) {
   }
 
   compositor_t comp = {0};
+
+  init_ui_ctx(&(comp.ctx));
+
   comp.nodes = (node_t *)malloc(sizeof(node_t) * MAX_NODES);
 
   window_t *main_window = &(comp.windows[0]);
@@ -64,19 +61,26 @@ i32 run_main_loop(void) {
   SDL_EventState(SDL_DROPFILE, SDL_ENABLE);
 
   colour_t bg_colour = {.abgr = 0xffffffff};
+  ui_elem_colours_t button_colours = (ui_elem_colours_t){
+      .fill = (colour_t){.abgr = 0xff89a83c},
+      .border = (colour_t){.abgr = 0xff768432},
+  };
+  ui_elem_colours_t io_node_colours = (ui_elem_colours_t){
+      .fill = (colour_t){.abgr = 0xff2c84b7},
+      .border = (colour_t){.abgr = 0xff315c89},
+  };
+  ui_elem_colours_t op_node_colours = (ui_elem_colours_t){
+      .fill = (colour_t){.abgr = 0xffad6c3a},
+      .border = (colour_t){.abgr = 0xff8e4a33},
+  };
 
-  i32 button_x = (toolbox->width - BUTTON_WIDTH) / 2;
-  for (u64 i = 0; i < COUNT_COMP_OPS; ++i) {
-    comp.buttons[i] = (button_t){.rect = (rect_t){
-                                     .topleft.x = button_x,
-                                     .topleft.y = i * (BUTTON_HEIGHT + 20) + 30,
-                                     .w = BUTTON_WIDTH,
-                                     .h = BUTTON_HEIGHT,
-                                 }};
-  }
+  i32 toolbox_button_x = (toolbox->width - BUTTON_WIDTH) / 2;
 
   while (comp.running) {
     while (SDL_PollEvent(&(comp.event))) {
+      handle_ui_events(&(comp.windows[comp.active_window - 1]), &(comp.ctx),
+                       &(comp.event));
+
       switch (comp.event.type) {
       case SDL_QUIT:
         comp.running = false;
@@ -94,6 +98,7 @@ i32 run_main_loop(void) {
             window_t *window = &(comp.windows[i]);
 
             if (id == window->id) {
+              comp.active_window = id;
               wnd = window;
               break;
             }
@@ -110,84 +115,12 @@ i32 run_main_loop(void) {
         }
 
         break;
-      case SDL_MOUSEBUTTONDOWN:
-        if (comp.event.button.windowID == main_window->id) {
-          if (comp.node_hovered != -1) {
-            comp.move_node = true;
-          }
-
-          comp.last_clicked_mouse_x = comp.event.button.x;
-          comp.last_clicked_mouse_y = comp.event.button.y;
-
-          break;
-        } else if (comp.event.button.windowID == toolbox->id) {
-          if (comp.button_hovered != -1) {
-            comp.button_clicked = comp.button_hovered;
-          }
-
-          break;
-        }
-      case SDL_MOUSEBUTTONUP:
-        comp.move_node = false;
-
-        if (comp.event.button.windowID == toolbox->id) {
-          if (comp.button_hovered >= 0 &&
-              comp.button_hovered == comp.button_clicked) {
-            add_node(&comp, NODE_TYPE_OP,
-                     (node_data_t){.func = ops[comp.button_hovered]},
-                     comp.last_clicked_mouse_x, comp.last_clicked_mouse_y);
-          }
-
-          comp.button_clicked = -1;
-        }
-
-        break;
-      case SDL_MOUSEMOTION:
-        comp.button_hovered = -1;
-
-        if (comp.event.motion.windowID == main_window->id) {
-          comp.mouse_x = comp.event.motion.x;
-          comp.mouse_y = comp.event.motion.y;
-
-          if (comp.move_node) {
-            i32 dx = comp.event.motion.xrel;
-            i32 dy = comp.event.motion.yrel;
-
-            node_t *node = &(comp.nodes[comp.node_hovered]);
-
-            node->rect.topleft.x += dx;
-            node->rect.topleft.y += dy;
-          } else {
-            comp.node_hovered = -1;
-
-            for (u64 i = comp.count - 1; i >= 0; --i) {
-              rect_t *rect = &(comp.nodes[i].rect);
-
-              if (aabb(rect, comp.mouse_x, comp.mouse_y)) {
-                comp.node_hovered = i;
-                break;
-              }
-            }
-          }
-
-          break;
-        } else if (comp.event.motion.windowID == toolbox->id) {
-          for (u64 i = COUNT_COMP_OPS - 1; i >= 0; --i) {
-            rect_t *rect = &(comp.buttons[i].rect);
-
-            if (aabb(rect, comp.event.motion.x, comp.event.motion.y)) {
-              comp.button_hovered = i;
-              break;
-            }
-          }
-
-          break;
-        }
       case SDL_DROPFILE:
         if (comp.event.drop.windowID == main_window->id) {
           node_data_t data = (node_data_t){.path = comp.event.drop.file};
 
-          add_node(&comp, NODE_TYPE_IO, data, comp.mouse_x, comp.mouse_y);
+          add_node(&comp, NODE_TYPE_IO, data, comp.ctx.mouse_x,
+                   comp.ctx.mouse_y, io_node_colours);
 
           break;
         }
@@ -198,23 +131,37 @@ i32 run_main_loop(void) {
       clear_window(&(comp.windows[i]), bg_colour);
     }
 
-    for (u64 i = 0; i < comp.count; ++i) {
-      node_t *node = &(comp.nodes[i]);
-      draw_node(main_window, node);
+    for (u64 i = 0; i < COUNT_COMP_OPS; ++i) {
+      rect_t rect = {
+          .topleft.x = toolbox_button_x,
+          .topleft.y = i * (BUTTON_HEIGHT + 20) + 30,
+          .w = BUTTON_WIDTH,
+          .h = BUTTON_HEIGHT,
+      };
+
+      if (button(toolbox, &(comp.ctx), rect, button_colours)) {
+        node_data_t data = (node_data_t){.func = ops[i]};
+
+        add_node(&comp, NODE_TYPE_OP, data, comp.ctx.mouse_x, comp.ctx.mouse_y,
+                 op_node_colours);
+      }
     }
 
-    for (u64 i = 0; i < COUNT_COMP_OPS; ++i) {
-      button_t *button = &(comp.buttons[i]);
-      draw_button(toolbox, button);
+    for (u64 i = 0; i < comp.count; ++i) {
+      comp.nodes[i].rect = node(main_window, &(comp.ctx), comp.nodes[i].rect,
+                                comp.nodes[i].colours);
     }
 
     for (u64 i = 0; i < MAX_WINDOWS; ++i) {
       swap_buffers(&(comp.windows[i]));
     }
+
+    reset_ui_ctx(&(comp.ctx));
   }
 
-  cleanup_window(toolbox);
-  cleanup_window(main_window);
+  for (u64 i = 0; i < MAX_WINDOWS; ++i) {
+    cleanup_window(&(comp.windows[i]));
+  }
 
   SDL_Quit();
 
@@ -222,7 +169,7 @@ i32 run_main_loop(void) {
 }
 
 void add_node(compositor_t *comp, node_type_t type, node_data_t data, i32 x,
-              i32 y) {
+              i32 y, ui_elem_colours_t colours) {
   if (comp->count + 1 >= MAX_NODES) {
     return;
   }
@@ -235,6 +182,7 @@ void add_node(compositor_t *comp, node_type_t type, node_data_t data, i32 x,
               .w = NODE_WIDTH,
               .h = NODE_HEIGHT,
           },
+      .colours = colours,
       .type = type,
       .data.path = data.path,
   };
diff --git a/src/nodes.c b/src/nodes.c
deleted file mode 100644
index 0e708b5..0000000
--- a/src/nodes.c
+++ /dev/null
@@ -1,28 +0,0 @@
-#include "nodes.h"
-#include "aliases/aliases.h"
-#include "window.h"
-#include <stdbool.h>
-
-typedef struct node_colours node_colours_t;
-struct node_colours {
-  colour_t fill;
-  colour_t border;
-};
-
-INTERNAL node_colours_t colours[COUNT_NODE_TYPES] = {
-    [NODE_TYPE_IO] =
-        (node_colours_t){
-            .fill = IO_NODE_FILL_COLOUR,
-            .border = IO_NODE_BORDER_COLOUR,
-        },
-    [NODE_TYPE_OP] =
-        (node_colours_t){
-            .fill = OP_NODE_FILL_COLOUR,
-            .border = OP_NODE_BORDER_COLOUR,
-        },
-};
-
-void draw_node(const window_t *wnd, const node_t *node) {
-  fill_rect(wnd, &(node->rect), colours[node->type].fill);
-  draw_rect(wnd, &(node->rect), colours[node->type].border);
-}
diff --git a/src/ui.c b/src/ui.c
index a5a71ba..0953838 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -1,6 +1,139 @@
 #include "ui.h"
+#include "SDL_events.h"
+#include "aliases/aliases.h"
+#include "window.h"
 
-bool aabb(const rect_t *rect, i32 x, i32 y) {
-  return x > rect->topleft.x && x <= rect->topleft.x + rect->w &&
-         y > rect->topleft.y && y <= rect->topleft.y + rect->h;
+bool aabb(const ui_elem_t *elem, i32 x, i32 y) {
+  return x > elem->rect.topleft.x && x <= elem->rect.topleft.x + elem->rect.w &&
+         y > elem->rect.topleft.y && y <= elem->rect.topleft.y + elem->rect.h;
+}
+
+void init_ui_ctx(ui_ctx_t *ctx) {
+  *ctx = (ui_ctx_t){0};
+  ctx->hovered = -1;
+  ctx->active = -1;
+}
+
+void reset_ui_ctx(ui_ctx_t *ctx) {
+  ctx->count = 0;
+  ctx->mouse_down = false;
+  ctx->mouse_up = false;
+}
+
+void handle_ui_events(const window_t *wnd, ui_ctx_t *ctx,
+                      const SDL_Event *event) {
+  switch (event->type) {
+  case SDL_MOUSEMOTION:
+    if (wnd->id == event->motion.windowID) {
+      ctx->mouse_x = event->motion.x;
+      ctx->mouse_y = event->motion.y;
+      ctx->wnd = wnd;
+
+      break;
+    }
+  case SDL_MOUSEBUTTONDOWN:
+    if (wnd->id == event->button.windowID) {
+      ctx->mouse_x = event->button.x;
+      ctx->mouse_y = event->button.y;
+      ctx->mouse_down = true;
+      ctx->wnd = wnd;
+    }
+
+    break;
+  case SDL_MOUSEBUTTONUP:
+    if (wnd->id == event->button.windowID) {
+      ctx->mouse_x = event->button.x;
+      ctx->mouse_y = event->button.y;
+      ctx->mouse_up = true;
+      ctx->wnd = wnd;
+    }
+
+    break;
+  }
+}
+
+bool button(const window_t *wnd, ui_ctx_t *ctx, rect_t rect,
+            ui_elem_colours_t colours) {
+  if (ctx->count + 1 >= MAX_UI_ELEMENTS) {
+    return false;
+  }
+
+  ui_elem_t elem = (ui_elem_t){
+      .id = (ctx->count)++,
+      .rect = rect,
+      .type = UI_ELEM_BUTTON,
+  };
+
+  fill_rect(wnd, rect, colours.fill);
+  draw_rect(wnd, rect, colours.border);
+
+  if (wnd != ctx->wnd || (ctx->active >= 0 && ctx->active != elem.id)) {
+    return false;
+  }
+
+  if (!aabb(&elem, ctx->mouse_x, ctx->mouse_y)) {
+    return false;
+  }
+
+  ctx->hovered = elem.id;
+
+  if (ctx->mouse_down) {
+    ctx->active = elem.id;
+  }
+
+  if (ctx->mouse_up && ctx->hovered == elem.id && ctx->active == elem.id) {
+    ctx->hovered = ctx->active = -1;
+    return true;
+  }
+
+  return false;
+}
+
+rect_t node(const window_t *wnd, ui_ctx_t *ctx, rect_t rect,
+            ui_elem_colours_t colours) {
+  if (ctx->count + 1 >= MAX_UI_ELEMENTS) {
+    return (rect_t){0};
+  }
+
+  ui_elem_t elem = (ui_elem_t){
+      .id = (ctx->count)++,
+      .rect = rect,
+      .type = UI_ELEM_NODE,
+  };
+
+  fill_rect(wnd, rect, colours.fill);
+  draw_rect(wnd, rect, colours.border);
+
+  if (wnd != ctx->wnd || (ctx->active >= 0 && ctx->active != elem.id)) {
+    return rect;
+  }
+
+  if (ctx->mouse_up) {
+    ctx->hovered = ctx->active = -1;
+    ctx->rel_x = ctx->rel_y = 0;
+    return rect;
+  }
+
+  if (ctx->hovered == elem.id && ctx->active == elem.id) {
+    return (rect_t){
+        .topleft.x = ctx->mouse_x + ctx->rel_x,
+        .topleft.y = ctx->mouse_y + ctx->rel_y,
+        .w = rect.w,
+        .h = rect.h,
+    };
+  }
+
+  if (!aabb(&elem, ctx->mouse_x, ctx->mouse_y)) {
+    return rect;
+  }
+
+  ctx->hovered = elem.id;
+
+  if (ctx->mouse_down) {
+    ctx->active = elem.id;
+    ctx->rel_x = rect.topleft.x - ctx->mouse_x;
+    ctx->rel_y = rect.topleft.y - ctx->mouse_y;
+  }
+
+  return rect;
 }
diff --git a/src/window.c b/src/window.c
index 5602fb0..de0c873 100644
--- a/src/window.c
+++ b/src/window.c
@@ -90,18 +90,18 @@ void draw_triangle(const window_t *wnd, const triangle_t *triangle,
   draw_line(wnd, &ln2, colour);
 }
 
-void draw_rect(const window_t *wnd, const rect_t *rect, colour_t colour) {
+void draw_rect(const window_t *wnd, rect_t rect, colour_t colour) {
   set_colour(wnd, colour);
 
-  SDL_Rect dst = {rect->topleft.x, rect->topleft.y, rect->w, rect->h};
+  SDL_Rect dst = {rect.topleft.x, rect.topleft.y, rect.w, rect.h};
 
   SDL_RenderDrawRect(wnd->renderer, &dst);
 }
 
-void fill_rect(const window_t *wnd, const rect_t *rect, colour_t colour) {
+void fill_rect(const window_t *wnd, rect_t rect, colour_t colour) {
   set_colour(wnd, colour);
 
-  SDL_Rect dst = {rect->topleft.x, rect->topleft.y, rect->w, rect->h};
+  SDL_Rect dst = {rect.topleft.x, rect.topleft.y, rect.w, rect.h};
 
   SDL_RenderFillRect(wnd->renderer, &dst);
 }