godot-ui-control

The full skill.

Original instructions from the publisher’s SKILL.md

# Godot UI / Control nodes (4.x)

Lay out responsive UI with `Control` anchors and `Container` nodes, style it with a
`Theme`, and make it navigable by keyboard and gamepad. Targets **Godot 4.7**.

## When to use

- Use when building HUDs, menus, inventories, dialog boxes, or settings screens with
  `Control`-derived nodes; arranging UI that adapts to window size; theming; or wiring
  focus navigation for controller/keyboard.

**When *not* to use:** in-world 2D nodes (`Node2D`/sprites) → `godot-nodes-scenes`;
animating UI transitions → `godot-animation` (Tween); genre UIs like card hands →
`card-game`/`visual-novel`. For full input rebinding → `input-systems`.

## Core workflow

1. **Use `Control` nodes for UI**, not `Node2D`. Controls have a rect (position + size),
   anchors, and participate in focus/theming.
2. **Anchor for responsiveness.** Anchors are fractions (0–1) of the parent rect that the
   Control's edges stick to. Use the editor's **Layout** presets (Top-Left, Full Rect,
   Center, etc.) instead of hand-placing pixels.
3. **Let Containers position children.** Put children in a `VBoxContainer`,
   `HBoxContainer`, `GridContainer`, `MarginContainer`, etc. — the container sets their
   position/size; you control flow with `size_flags`. Don't set child anchors inside a
   container (it overrides them).
4. **Style with a `Theme`.** Assign a `Theme` resource on a top Control; children inherit
   it. Override per-node with theme overrides only when necessary.
5. **Wire focus** so gamepad/keyboard can move between buttons; set a default focused
   control and define neighbors or rely on auto-neighbor.
6. **Connect signals** (`pressed`, `toggled`, `text_submitted`, `value_changed`).

## Patterns

### 1. Responsive layout with anchors (code form)

```gdscript
extends Control

func _ready() -> void:
    # Stretch this panel to fill its parent (equivalent to the "Full Rect" preset).
    anchors_preset = Control.PRESET_FULL_RECT
    # Or set anchors manually: all four edges at the parent's far corners.
    # anchor_left = 0; anchor_top = 0; anchor_right = 1; anchor_bottom = 1
```

### 2. A menu built from containers + button signals

```gdscript
extends VBoxContainer    # children stack vertically, auto-sized

func _ready() -> void:
    for child in get_children():
        if child is Button:
            child.pressed.connect(_on_button_pressed.bind(child.name))
    # Give the first button focus so a gamepad can navigate immediately.
    if get_child_count() > 0:
        (get_child(0) as Control).grab_focus()

func _on_button_pressed(which: StringName) -> void:
    match which:
        "PlayButton":  get_tree().change_scene_to_file("res://game.tscn")
        "QuitButton":  get_tree().quit()
```

### 3. Size flags: make one child expand to fill leftover space

```gdscript
# In a HBoxContainer: a label on the left, a spacer that eats remaining width.
func _ready() -> void:
    $Label.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
    $Spacer.size_flags_horizontal = Control.SIZE_EXPAND_FILL   # grows to fill
```

### 4. Theme override for one node (without a full Theme resource)

```gdscript
func _ready() -> void:
    # Per-node overrides: use add_theme_* (type-specific setters).
    $Title.add_theme_font_size_override("font_size", 32)
    $Title.add_theme_color_override("font_color", Color.GOLD)
    $Panel.add_theme_stylebox_override("panel", preload("res://ui/panel.stylebox.tres"))
```

## Pitfalls

- **Mixing manual position with Containers.** A child of a `Container` cannot set its own
  position/anchors — the container owns layout. To free-place, take the node out of the
  container or use a plain `Control`/`PanelContainer` wrapper.
- **Anchors vs offsets.** Anchors are fractions of the parent; offsets are pixel deltas
  from the anchored point. Set anchors via presets, then nudge with offsets. Setting only
  position while anchors are at 0 makes UI not scale with the window.
- **`Node2D` for UI.** Buttons/labels parented under a `Node2D` won't theme or take focus
  correctly. Keep UI under a `CanvasLayer`/`Control` subtree.
- **Focus lost on gamepad.** If nothing is focused, directional input does nothing. Call
  `grab_focus()` on an initial control and ensure `focus_mode` is not `FOCUS_NONE`.
- **Theme vs theme override.** A `Theme` resource styles a whole subtree; `add_theme_*`
  overrides one node. Overusing per-node overrides defeats centralized theming.
- **`rect_*` properties are renamed.** Godot 3's `rect_size`/`rect_position`/`rect_min_size`
  are now `size`/`position`/`custom_minimum_size` in 4.x.
- **`mouse_filter`** on a full-rect Control can swallow clicks meant for nodes beneath it;
  set `MOUSE_FILTER_IGNORE` on purely decorative panels.

## References

- For the anchor/offset math, every Container type, building/extending Theme and StyleBox
  resources, focus neighbor wiring, and `CanvasLayer` for HUDs, read
  `references/layout-and-theming.md`.

## Related skills

- `game-ui-ux` — cross-engine UI/UX: responsive scaling, safe areas, focus navigation, screen flow.
- `godot-animation` — Tween-based UI transitions and juicing.
- `godot-signals-groups` — connecting UI events to game logic.
- `input-systems` — rebindable input and multi-device focus.
- `card-game` / `visual-novel` — UI-heavy genre templates.