diff --git a/demo/demo.c b/demo/demo.c
index ae94f0b..81413fd 100644
--- a/demo/demo.c
+++ b/demo/demo.c
@@ -267,7 +267,7 @@ color_picker(struct gui_panel_layout *panel, struct control_window *control,
 
     b = gui_panel_slider(panel, 0, b, 255, 10);
     color.b = (gui_byte)b;
-    color.b = (gui_byte)gui_panel_spinner(panel, 0, (gui_int)color.b, 255, 1, &control->spinner_b_active);
+    color.b = (gui_byte)gui_panel_spinner(panel, 0,(gui_int)color.b, 255, 1, &control->spinner_b_active);
 
     a = gui_panel_slider(panel, 0, a, 255, 10);
     color.a = (gui_byte)a;
@@ -286,10 +286,11 @@ color_tab(struct gui_panel_layout *panel, struct control_window *control, struct
         "Editbox Border:", "Spinner:", "Spinner Border:", "Selector:", "Selector Border:",
         "Histo:", "Histo Bars:", "Histo Negative:", "Histo Hovering:", "Plot:", "Plot Lines:",
         "Plot Hightlight:", "Scrollbar:", "Scrollbar Cursor:", "Scrollbar Border:",
-        "Table lines:", "Scaler:"
+        "Table lines:", "Shelf:", "Shelf Text:", "Shelf Active:", "Shelf Active Text:", "Scaler:"
     };
+
     if (control->picker_active) {
-        control->color = color_picker(panel, control, labels[control->current_color], control->color);
+        control->color = color_picker(panel,control,labels[control->current_color], control->color);
         gui_panel_row(panel, 30, 3);
         gui_panel_seperator(panel, 1);
         if (gui_panel_button_text(panel, "ok", GUI_BUTTON_DEFAULT)) {
diff --git a/demo/demo.lua b/demo/demo.lua
new file mode 100644
index 0000000..5e36c36
--- /dev/null
+++ b/demo/demo.lua
@@ -0,0 +1,25 @@
+gui = require(gui);
+
+demo = {};
+
+function init_demo(stack, font)
+    demo.font = font;
+    demo.canvas = gui.buffer.canvas();
+    demo.config = gui.panel.config();
+    demo.layout = gui.panel.layout();
+    demo.tab = gui.panel.layout();
+
+    demo.memory = gui.buffer.memory(8 * 1024);
+    demo.buffer = gui.buffer.new(demo.memory);
+    demo.panel = gui.hook.new(50, 50, 200, 400, demo.config, font);
+    gui.stack.push(stack, demo.panel);
+end
+
+function update_demo(stack, input, width, height)
+    gui.buffer.begin(demo.canvas, demo.buffer, width, height);
+    gui.panel.hook.begin(demo.layout, demo.panel, stack, "Demo", demo.canvas, input);
+    if gui.panel.button(demo.layout, "Button") then print("button pressed!") end
+    gui.panel.hook.end(demo.layout, demo.panel);
+    gui.buffer.end(demo.panel:output(), demo.buffer, demo.canvas);
+end
+
diff --git a/demo/opengl.c b/demo/opengl.c
index 2c25854..0df2ba2 100644
--- a/demo/opengl.c
+++ b/demo/opengl.c
@@ -428,29 +428,27 @@ execute(struct gui_command_list *list, int width, int height)
     glPushMatrix();
     glLoadIdentity();
 
-    cmd = gui_list_begin(list);
-    while (cmd) {
+    gui_list_for_each(cmd, list) {
         switch (cmd->type) {
         case GUI_COMMAND_NOP: break;
         case GUI_COMMAND_SCISSOR: {
-            const struct gui_command_scissor *s = (const void*)cmd;
+            const struct gui_command_scissor *s = GUI_FETCH(scissor, cmd);
             glScissor(s->x, height - (s->y + s->h), s->w, s->h);
         } break;
         case GUI_COMMAND_LINE: {
-            const struct gui_command_line *l = (const void*)cmd;
+            const struct gui_command_line *l = GUI_FETCH(line, cmd);
             draw_line(l->begin[0], l->begin[1], l->end[0], l->end[1], l->color);
         } break;
         case GUI_COMMAND_RECT: {
-            const struct gui_command_rect *r = (const void*)cmd;
+            const struct gui_command_rect *r = GUI_FETCH(rect, cmd);
             draw_rect(r->x, r->y, r->w, r->h, r->color);
         } break;
         case GUI_COMMAND_CIRCLE: {
-            unsigned i;
-            const struct gui_command_circle *c = (const void*)cmd;
+            const struct gui_command_circle *c = GUI_FETCH(circle, cmd);
             draw_circle(c->x, c->y, (float)c->w / 2.0f, c->color);
         } break;
         case GUI_COMMAND_TRIANGLE: {
-            const struct gui_command_triangle *t = (const void*)cmd;
+            const struct gui_command_triangle *t = GUI_FETCH(triangle, cmd);
             glColor4ub(t->color.r, t->color.g, t->color.b, t->color.a);
             glBegin(GL_TRIANGLES);
             glVertex2f(t->a[0], t->a[1]);
@@ -459,14 +457,13 @@ execute(struct gui_command_list *list, int width, int height)
             glEnd();
         } break;
         case GUI_COMMAND_TEXT: {
-            const struct gui_command_text *t = (const void*)cmd;
+            const struct gui_command_text *t = GUI_FETCH(text, cmd);
             font_draw_text(t->font, t->x, t->y, t->h, t->fg, t->string, t->length);
         } break;
         case GUI_COMMAND_IMAGE:
         case GUI_COMMAND_MAX:
         default: break;
         }
-        cmd = gui_list_next(list, cmd);
     }
 
     glBindTexture(GL_TEXTURE_2D, 0);
@@ -480,12 +477,9 @@ execute(struct gui_command_list *list, int width, int height)
 static void
 draw(struct gui_panel_stack *stack, int width, int height)
 {
-    struct gui_panel_hook *iter = stack->begin;
-    if (!stack->count) return;
-    while (iter) {
+    struct gui_panel_hook *iter;
+    gui_stack_for_each(iter, stack)
         execute(gui_hook_output(iter), width, height);
-        iter = iter->next;
-    }
 }
 
 static void
diff --git a/demo/win32.c b/demo/win32.c
index 44ae988..7403c45 100644
--- a/demo/win32.c
+++ b/demo/win32.c
@@ -272,56 +272,50 @@ static void
 execute(XSurface *surf, struct gui_command_list *list)
 {
     const struct gui_command *cmd;
-    if (!list->count) return;
-    cmd = gui_list_begin(list);
-    while (cmd) {
+    gui_list_for_each(cmd, list) {
         switch (cmd->type) {
         case GUI_COMMAND_NOP: break;
         case GUI_COMMAND_SCISSOR: {
-            const struct gui_command_scissor *s = (const void*)cmd;
+            const struct gui_command_scissor *s = GUI_FETCH(scissor, cmd);
             surface_scissor(surf, s->x, s->y, s->w, s->h);
         } break;
         case GUI_COMMAND_LINE: {
-            const struct gui_command_line *l = (const void*)cmd;
+            const struct gui_command_line *l = GUI_FETCH(line, cmd);
             surface_draw_line(surf, l->begin[0], l->begin[1], l->end[0],
                 l->end[1], l->color.r, l->color.g, l->color.b);
         } break;
         case GUI_COMMAND_RECT: {
-            const struct gui_command_rect *r = (const void*)cmd;
+            const struct gui_command_rect *r = GUI_FETCH(rect, cmd);
             surface_draw_rect(surf, r->x, r->y, r->w, r->h,
                 r->color.r, r->color.g, r->color.b);
         } break;
         case GUI_COMMAND_CIRCLE: {
-            const struct gui_command_circle *c = (const void*)cmd;
+            const struct gui_command_circle *c = GUI_FETCH(circle, cmd);
             surface_draw_circle(surf, c->x, c->y, c->w, c->h,
                 c->color.r, c->color.g, c->color.b);
         } break;
         case GUI_COMMAND_TRIANGLE: {
-            const struct gui_command_triangle *t = (const void*)cmd;
+            const struct gui_command_triangle *t = GUI_FETCH(triangle, cmd);
             surface_draw_triangle(surf, t->a[0], t->a[1], t->b[0], t->b[1],
                 t->c[0], t->c[1], t->color.r, t->color.g, t->color.b);
         } break;
         case GUI_COMMAND_TEXT: {
-            const struct gui_command_text *t = (const void*)cmd;
+            const struct gui_command_text *t = GUI_FETCH(text, cmd);
             XWindow *win = t->font;
             surface_draw_text(surf, win->font, t->x, t->y, t->w, t->h, (const char*)t->string,
                     t->length, t->bg.r, t->bg.g, t->bg.b, t->fg.r, t->fg.g, t->fg.b);
         } break;
         default: break;
         }
-        cmd = gui_list_next(list, cmd);
     }
 }
 
 static void
 draw(XSurface *surf, struct gui_panel_stack *stack)
 {
-    struct gui_panel_hook *iter = stack->begin;
-    if (!stack->count) return;
-    while (iter) {
+    struct gui_panel_hook *iter;
+    gui_stack_for_each(iter, stack)
         execute(surf, gui_hook_output(iter));
-        iter = iter->next;
-    }
 }
 
 static void
diff --git a/demo/xlib.c b/demo/xlib.c
index ebd6854..cb4e4a1 100644
--- a/demo/xlib.c
+++ b/demo/xlib.c
@@ -302,35 +302,33 @@ static void
 execute(XSurface *surf, struct gui_command_list *list)
 {
     const struct gui_command *cmd;
-    if (!list->count) return;
-    cmd = gui_list_begin(list);
-    while (cmd) {
+    gui_list_for_each(cmd, list) {
         switch (cmd->type) {
         case GUI_COMMAND_NOP: break;
         case GUI_COMMAND_SCISSOR: {
-            const struct gui_command_scissor *s = (const void*)cmd;
+            const struct gui_command_scissor *s = GUI_FETCH(scissor, cmd);
             surface_scissor(surf, s->x, s->y, s->w, s->h);
         } break;
         case GUI_COMMAND_LINE: {
-            const struct gui_command_line *l = (const void*)cmd;
+            const struct gui_command_line *l = GUI_FETCH(line, cmd);
             surface_draw_line(surf, l->begin[0], l->begin[1], l->end[0],
                 l->end[1], l->color);
         } break;
         case GUI_COMMAND_RECT: {
-            const struct gui_command_rect *r = (const void*)cmd;
+            const struct gui_command_rect *r = GUI_FETCH(rect, cmd);
             surface_draw_rect(surf, r->x, r->y, r->w, r->h, r->color);
         } break;
         case GUI_COMMAND_CIRCLE: {
-            const struct gui_command_circle *c = (const void*)cmd;
+            const struct gui_command_circle *c = GUI_FETCH(circle, cmd);
             surface_draw_circle(surf, c->x, c->y, c->w, c->h, c->color);
         } break;
         case GUI_COMMAND_TRIANGLE: {
-            const struct gui_command_triangle *t = (const void*)cmd;
+            const struct gui_command_triangle *t = GUI_FETCH(triangle, cmd);
             surface_draw_triangle(surf, t->a[0], t->a[1], t->b[0], t->b[1],
                 t->c[0], t->c[1], t->color);
         } break;
         case GUI_COMMAND_TEXT: {
-            const struct gui_command_text *t = (const void*)cmd;
+            const struct gui_command_text *t = GUI_FETCH(text, cmd);
             surface_draw_text(surf, t->x, t->y, t->w, t->h, (const char*)t->string,
                     t->length, t->font, t->bg, t->fg);
         } break;
@@ -338,19 +336,15 @@ execute(XSurface *surf, struct gui_command_list *list)
         case GUI_COMMAND_MAX:
         default: break;
         }
-        cmd = gui_list_next(list, cmd);
     }
 }
 
 static void
 draw(XSurface *surf, struct gui_panel_stack *stack)
 {
-    struct gui_panel_hook *iter = stack->begin;
-    if (!stack->count) return;
-    while (iter) {
+    struct gui_panel_hook *iter;
+    gui_stack_for_each(iter, stack)
         execute(surf, gui_hook_output(iter));
-        iter = iter->next;
-    }
 }
 
 static void
diff --git a/gui.c b/gui.c
index ea3674c..16cd524 100644
--- a/gui.c
+++ b/gui.c
@@ -1359,6 +1359,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     ASSERT(layout);
     ASSERT(canvas);
 
+    /* check arguments */
     if (!panel || !canvas || !layout)
         return gui_false;
     if (panel->flags & GUI_PANEL_HIDDEN) {
@@ -1369,10 +1370,12 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         return gui_false;
     }
 
+    /* calculate header */
     config = panel->config;
     layout->header_height = panel->font.height + 3 * config->item_padding.y;
     layout->header_height += config->panel_padding.y;
 
+    /* make sure input can be NULL */
     mouse_x = (in) ? in->mouse_pos.x : -1;
     mouse_y = (in) ? in->mouse_pos.y : -1;
     prev_x = (in) ? in->mouse_prev.x : -1;
@@ -1380,6 +1383,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     clicked_x = (in) ? in->mouse_clicked_pos.x : -1;
     clicked_y = (in) ? in->mouse_clicked_pos.y : -1;
 
+    /* panel movement logic */
     if (panel->flags & GUI_PANEL_MOVEABLE) {
         gui_bool incursor;
         const gui_float move_x = panel->x;
@@ -1394,6 +1398,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         }
     }
 
+    /* panel scaling logic */
     if (panel->flags & GUI_PANEL_SCALEABLE) {
         gui_bool incursor;
         gui_float scaler_w = MAX(0, config->scaler_size.x - config->item_padding.x);
@@ -1410,6 +1415,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         }
     }
 
+    /* setup layout */
     layout->x = panel->x;
     layout->y = panel->y;
     layout->w = panel->w;
@@ -1427,6 +1433,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     layout->row_height = 0;
     layout->offset = panel->offset;
 
+    /* special case for shelfs which do not have a header */
     if (!(panel->flags & GUI_PANEL_NO_HEADER)) {
         header = &config->colors[GUI_COLOR_HEADER];
         header_x = panel->x + config->panel_padding.x;
@@ -1436,6 +1443,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     } else layout->header_height = 1;
     layout->row_height = layout->header_height + 2 * config->item_spacing.y;
 
+    /* add footer at the end of the panel */
     footer_h = config->scaler_size.y + config->item_padding.y;
     if ((panel->flags & GUI_PANEL_SCROLLBAR) && !panel->minimized) {
         gui_float footer_x, footer_y, footer_w;
@@ -1446,6 +1454,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
             config->colors[GUI_COLOR_PANEL]);
     }
 
+    /* update panel state which is either active or not active  */
     if (!(panel->flags & GUI_PANEL_TAB)) {
         panel->flags |= GUI_PANEL_SCROLLBAR;
         if (in && in->mouse_down) {
@@ -1455,6 +1464,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         }
     }
 
+    /* clipping rectangle for scrollbars */
     layout->clip.x = panel->x;
     layout->clip.w = panel->w;
     layout->clip.y = panel->y + layout->header_height - 1;
@@ -1464,6 +1474,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     }
     else layout->clip.h = null_rect.h;
 
+    /* panel hidding  */
     if ((panel->flags & GUI_PANEL_CLOSEABLE) && (!(panel->flags & GUI_PANEL_NO_HEADER))) {
         const gui_char *X = (const gui_char*)"x";
         const gui_size text_width = panel->font.width(panel->font.userdata, X, 1);
@@ -1474,6 +1485,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         canvas->draw_text(canvas->userdata, close_x, close_y, close_w, close_h,
             X, 1, &panel->font, config->colors[GUI_COLOR_HEADER], config->colors[GUI_COLOR_TEXT]);
 
+
         header_w -= close_w;
         header_x += close_h - config->item_padding.x;
         if (in && INBOX(mouse_x, mouse_y, close_x, close_y, close_w, close_h)) {
@@ -1484,6 +1496,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
         }
     }
 
+    /* panel minimizing */
     if ((panel->flags & GUI_PANEL_MINIMIZABLE) && (!(panel->flags & GUI_PANEL_NO_HEADER))) {
         gui_size text_width;
         gui_float min_x, min_y, min_w, min_h;
@@ -1510,6 +1523,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
     }
     layout->valid = !(panel->minimized || (panel->flags & GUI_PANEL_HIDDEN));
 
+    /* panel title */
     if (text && !(panel->flags & GUI_PANEL_NO_HEADER)) {
         const gui_size text_len = strsiz(text);
         const gui_float label_x = header_x + config->item_padding.x;
@@ -1521,6 +1535,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
             config->colors[GUI_COLOR_TEXT]);
     }
 
+    /* panels have an empty space at the bottom that needs to be filled */
     if (panel->flags & GUI_PANEL_SCROLLBAR) {
         const struct gui_color *color = &config->colors[GUI_COLOR_PANEL];
         layout->width = panel->w - config->scrollbar_width;
@@ -1531,6 +1546,7 @@ gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel *panel,
                 panel->w, panel->h - layout->header_height, *color);
     }
 
+    /* draws the border of the header */
     if (panel->flags & GUI_PANEL_BORDER) {
         const struct gui_color *color = &config->colors[GUI_COLOR_BORDER];
         const gui_float width = (panel->flags & GUI_PANEL_SCROLLBAR) ?
@@ -2056,6 +2072,7 @@ gui_panel_spinner(struct gui_panel_layout *layout, gui_int min, gui_int value,
     config = layout->config;
     canvas = layout->canvas;
 
+    /* up button */
     button.border = 1;
     button_y = bounds.y;
     button_h = bounds.h / 2;
@@ -2070,6 +2087,8 @@ gui_panel_spinner(struct gui_panel_layout *layout, gui_int min, gui_int value,
     button.highlight_content = config->colors[GUI_COLOR_TEXT];
     button_up_clicked = gui_button_triangle(canvas, button_x, button_y, button_w, button_h,
         GUI_UP, GUI_BUTTON_DEFAULT, &button, layout->input);
+
+    /* down button */
     button_y = bounds.y + button_h;
     button_down_clicked = gui_button_triangle(canvas, button_x, button_y, button_w, button_h,
         GUI_DOWN, GUI_BUTTON_DEFAULT, &button, layout->input);
@@ -2090,6 +2109,7 @@ gui_panel_spinner(struct gui_panel_layout *layout, gui_int min, gui_int value,
     len = gui_edit(canvas, field_x, field_y, field_w, field_h, (gui_char*)string,
             len, MAX_NUMBER_BUFFER, &is_active, &field,GUI_INPUT_FLOAT,
             layout->input, &layout->font);
+
     if (old_len != len)
         strtoi(&value, string, len);
     if (active) *active = is_active;
@@ -2126,6 +2146,7 @@ gui_panel_selector(struct gui_panel_layout *layout, const char *items[],
     canvas->draw_rect(canvas->userdata, bounds.x + 1, bounds.y + 1, bounds.w - 2, bounds.h - 2,
             config->colors[GUI_COLOR_SELECTOR]);
 
+    /* down button */
     button.border = 1;
     button_y = bounds.y;
     button_h = bounds.h / 2;
@@ -2141,12 +2162,14 @@ gui_panel_selector(struct gui_panel_layout *layout, const char *items[],
     button_down_clicked = gui_button_triangle(canvas, button_x, button_y, button_w,
         button_h, GUI_UP, GUI_BUTTON_DEFAULT, &button, layout->input);
 
+    /* up button */
     button_y = bounds.y + button_h;
     button_up_clicked = gui_button_triangle(canvas, button_x, button_y, button_w,
         button_h, GUI_DOWN, GUI_BUTTON_DEFAULT, &button,  layout->input);
     item_current = (button_down_clicked && item_current < item_count-1) ?
         item_current+1 : (button_up_clicked && item_current > 0) ? item_current-1 : item_current;
 
+    /* current item */
     label_x = bounds.x + config->item_padding.x;
     label_y = bounds.y + config->item_padding.y;
     label_w = bounds.w - (button_w + 2 * config->item_padding.x);
@@ -2608,12 +2631,14 @@ gui_panel_shelf_begin(struct gui_panel_layout *parent, struct gui_panel_layout *
     if (!INTERSECT(c->x, c->y, c->w, c->h, bounds.x, bounds.y, bounds.w, bounds.h))
         goto failed;
 
+    /* shelf header space */
     header_x = bounds.x;
     header_y = bounds.y;
     header_w = bounds.w;
     header_h = config->panel_padding.y + 3 * config->item_padding.y + parent->font.height;
     item_width = (header_w - (gui_float)size) / (gui_float)size;
 
+    /* shelf selection tabs */
     for (i = 0; i < size; i++) {
         struct gui_button button;
         gui_float button_x, button_y;
@@ -2704,6 +2729,8 @@ gui_panel_end(struct gui_panel_layout *layout, struct gui_panel *panel)
     if (!(panel->flags & GUI_PANEL_TAB))
         canvas->scissor(canvas->userdata, layout->x, layout->y, layout->w + 1, layout->h + 1);
 
+    /* @NOTE(vurtun): panel scrollbar at the end of the panel since the final height
+     * of the panel is not known at the beginning of the panel and can only now be calculated. */
     if (panel->flags & GUI_PANEL_SCROLLBAR && layout->valid) {
         struct gui_scroll scroll;
         gui_float panel_y;
@@ -2732,6 +2759,7 @@ gui_panel_end(struct gui_panel_layout *layout, struct gui_panel *panel)
                         config->colors[GUI_COLOR_PANEL]);
     } else layout->height = layout->at_y - layout->y;
 
+    /* draws the scaling triangle in the footer of the panel */
     if ((panel->flags & GUI_PANEL_SCALEABLE) && layout->valid) {
         struct gui_color col = config->colors[GUI_COLOR_SCALER];
         gui_float scaler_w = MAX(0, config->scaler_size.x - config->item_padding.x);
@@ -2742,6 +2770,7 @@ gui_panel_end(struct gui_panel_layout *layout, struct gui_panel *panel)
             scaler_x + scaler_w, scaler_y + scaler_h, scaler_x, scaler_y + scaler_h, col);
     }
 
+    /* draw the border for the body of the panel */
     if (panel->flags & GUI_PANEL_BORDER) {
         const gui_float width = (panel->flags & GUI_PANEL_SCROLLBAR) ?
                 layout->width + config->scrollbar_width : layout->width;
diff --git a/gui.h b/gui.h
index fe3cd5e..ca04289 100644
--- a/gui.h
+++ b/gui.h
@@ -460,6 +460,45 @@ struct gui_panel_stack {
 };
 
 
+
+/* Layout */
+struct gui_layout_ratio {
+    gui_float left;
+    gui_float center;
+    gui_float right;
+};
+
+enum gui_layout_index {
+    GUI_SLOT_TOP,
+    GUI_SLOT_BOTTOM,
+    GUI_SLOT_LEFT,
+    GUI_SLOT_CENTER,
+    GUI_SLOT_RIGHT,
+    GUI_SLOT_MAX
+};
+
+struct gui_layout_slots {
+    struct gui_panel_hook *top;
+    struct gui_panel_hook *bottom;
+    struct gui_panel_hook *left;
+    struct gui_panel_hook *center;
+    struct gui_panel_hook *right;
+};
+
+union gui_layout_slot_data {
+    struct gui_layout_slots slot;
+    struct gui_panel_hook *at[GUI_SLOT_MAX];
+};
+
+struct gui_layout {
+    gui_size width, height;
+    struct gui_panel_stack stack;
+    struct gui_layout_ratio horizontal;
+    struct gui_layout_ratio vertical;
+    union gui_layout_slot_data slots;
+};
+
+
 /* Input */
 gui_size gui_utf_decode(const gui_char*, gui_long*, gui_size);
 gui_size gui_utf_encode(gui_long, gui_char*, gui_size);
@@ -507,6 +546,8 @@ void gui_buffer_end(struct gui_command_list*, struct gui_command_buffer*,
 
 
 /* List */
+#define GUI_FETCH(t,c) (const struct gui_command_##t*)c
+#define gui_list_for_each(i, l) for (i = gui_list_begin(l); i != NULL; i = gui_list_next(l, i))
 const struct gui_command* gui_list_begin(const struct gui_command_list*);
 const struct gui_command* gui_list_next(const struct gui_command_list*,
                         const struct gui_command*);
@@ -556,6 +597,9 @@ gui_bool gui_panel_begin(struct gui_panel_layout *layout, struct gui_panel*,
 gui_bool gui_panel_begin_stacked(struct gui_panel_layout*, struct gui_panel*,
                     struct gui_panel_stack*, const char*, const struct gui_canvas*,
                     const struct gui_input*);
+gui_bool gui_panel_begin_tiled(struct gui_panel_layout*, struct gui_panel*,
+                    struct gui_panel_layout*, const char*, const struct gui_canvas*,
+                    const struct gui_input*);
 void gui_panel_row(struct gui_panel_layout*, gui_float height, gui_size cols);
 gui_bool gui_panel_widget(struct gui_rect*, struct gui_panel_layout*);
 void gui_panel_seperator(struct gui_panel_layout*, gui_size cols);
@@ -613,20 +657,29 @@ gui_size gui_panel_shelf_begin(struct gui_panel_layout*, struct gui_panel_layout
 gui_float gui_panel_shelf_end(struct gui_panel_layout*, struct gui_panel_layout *shelf);
 void gui_panel_end(struct gui_panel_layout*, struct gui_panel*);
 
+
 /* Hook */
 #define gui_hook_panel(h) (&((h)->GUI_HOOK_PANEL_NAME))
 #define gui_hook_output(h) (&((h)->GUI_HOOK_OUTPUT_NAME))
 #define gui_panel_hook_init(hook, x, y, w, h, flags, config, font)\
-    gui_panel_init(&(*(hook)).GUI_HOOK_PANEL_NAME, x, y, w, h, flags, config, font)
+    gui_panel_init(gui_hook_panel(hook), x, y, w, h, flags, config, font)
 #define gui_panel_hook_begin(layout, hook, stack, title, canvas, in)\
-    gui_panel_begin_stacked(layout, &(*(hook)).GUI_HOOK_PANEL_NAME, stack, title, canvas, in)
+    gui_panel_begin_stacked(layout, gui_hook_panel(hook), stack, title, canvas, in)
 #define gui_panel_hook_end(layout, hook)\
-    gui_panel_end((layout), &(hook)->GUI_HOOK_PANEL_NAME)
+    gui_panel_end((layout), gui_hook_panel(hook))
 
 /* Stack  */
+#define gui_stack_begin(s) ((s)->begin)
+#define gui_stack_end(s) ((s)->end)
 void gui_stack_clear(struct gui_panel_stack*);
 void gui_stack_push(struct gui_panel_stack*, struct gui_panel_hook*);
 void gui_stack_pop(struct gui_panel_stack*, struct gui_panel_hook*);
+#define gui_stack_for_each(i, s) for (i = gui_stack_begin(s); i != NULL; i = (i)->next)
+
+/* Layout  */
+void gui_layout_init(struct gui_layout*);
+void gui_layout_add(struct gui_layout*, struct gui_panel_hook*, enum gui_layout_index);
+void gui_layout_remove(struct gui_layout*, struct gui_panel_hook*);
 
 
 #ifdef __cplusplus