Added selectable container that can be focused with keyboard shortcut.

scripts/selectable_container.gd

@@ -0,0 +1,152 @@
+@tool
+class_name SelectableContainer
+extends MarginContainer
+
+signal activated
+signal deactivated
+
+@export var title: String = "Panel":
+	set(value):
+		title = value
+		_refresh_header()
+@export var focus_key: Key = KEY_F1:
+	set(value):
+		focus_key = value
+		_refresh_header()
+@export_node_path("Control") var initial_focus: NodePath
+
+var is_active: bool = false
+var _last_focus: Control
+var _shortcut_available: bool = true
+var _initial_focus_control: Control
+@onready var content: VBoxContainer = $MarginContainer/VBoxContainer/Content
+@onready var _panel: PanelContainer = $PanelContainer
+@onready var _shortcut: Button = $MarginContainer/VBoxContainer/HBoxContainer/Button
+
+func _ready() -> void:
+	_refresh_header()
+	if Engine.is_editor_hint():
+		return
+	# Resolve authored paths before reparenting changes the runtime hierarchy.
+	_initial_focus_control = get_node_or_null(initial_focus) as Control
+	for child in get_children():
+		_route_content_child(child)
+	child_entered_tree.connect(_on_child_entered_tree)
+	add_to_group("keyboard_focus_containers")
+	focus_mode = Control.FOCUS_NONE
+	_shortcut.focus_mode = Control.FOCUS_NONE
+	_shortcut.pressed.connect(activate)
+	for other in get_tree().get_nodes_in_group("keyboard_focus_containers"):
+		if other != self and other.get_viewport() == get_viewport() and other.focus_key == focus_key and other._shortcut_available:
+			_shortcut_available = false
+			_shortcut.disabled = true
+			_shortcut.tooltip_text = "Shortcut already assigned to " + other.title
+			push_warning("Duplicate panel shortcut: " + OS.get_keycode_string(focus_key))
+			break
+	get_viewport().gui_focus_changed.connect(_on_focus_changed)
+	visibility_changed.connect(_on_visibility_changed)
+	_update_style()
+	content.focus_behavior_recursive = Control.FOCUS_BEHAVIOR_DISABLED
+
+func _refresh_header() -> void:
+	var label := get_node_or_null("MarginContainer/VBoxContainer/HBoxContainer/Label") as Label
+	var badge := get_node_or_null("MarginContainer/VBoxContainer/HBoxContainer/Button") as Button
+	if label != null:
+		label.text = title
+	if badge != null:
+		badge.text = OS.get_keycode_string(focus_key) + (" · ACTIVE" if is_active else "")
+
+func _on_child_entered_tree(child: Node) -> void:
+	# SceneTree may still be adding the node when this signal fires.
+	_route_content_child.call_deferred(child)
+
+func _route_content_child(child: Node) -> void:
+	if not is_instance_valid(child) or child.get_parent() != self:
+		return
+	if child == _panel or child == $MarginContainer:
+		return
+	child.reparent(content, false)
+
+func activate() -> void:
+	if Engine.is_editor_hint() or not is_visible_in_tree() or not _shortcut_available:
+		return
+	for other in get_tree().get_nodes_in_group("keyboard_focus_containers"):
+		if other != self and other.get_viewport() == get_viewport():
+			other.deactivate()
+	var was_active := is_active
+	is_active = true
+	focus_mode = Control.FOCUS_ALL
+	content.focus_behavior_recursive = Control.FOCUS_BEHAVIOR_ENABLED
+	_update_style()
+	var target: Control = _initial_focus_control if is_instance_valid(_initial_focus_control) else null
+	if is_instance_valid(_last_focus) and _last_focus.is_visible_in_tree():
+		target = _last_focus
+	if target != null and target.is_visible_in_tree() and target.get_focus_mode_with_override() != Control.FOCUS_NONE:
+		target.grab_focus()
+	else:
+		var controls := _focusable_controls(content)
+		if controls.is_empty():
+			grab_focus()
+		else:
+			controls[0].grab_focus()
+	if not was_active:
+		activated.emit()
+
+func deactivate() -> void:
+	if not is_active:
+		return
+	is_active = false
+	focus_mode = Control.FOCUS_NONE
+	var focus_owner := get_viewport().gui_get_focus_owner()
+	if focus_owner == self or (focus_owner != null and is_ancestor_of(focus_owner)):
+		focus_owner.release_focus()
+	content.focus_behavior_recursive = Control.FOCUS_BEHAVIOR_DISABLED
+	_update_style()
+	deactivated.emit()
+
+func _input(event: InputEvent) -> void:
+	if Engine.is_editor_hint() or not event is InputEventKey or not is_visible_in_tree():
+		return
+	var key := event as InputEventKey
+	if key.keycode == focus_key and not key.alt_pressed and not key.ctrl_pressed and not key.meta_pressed and not key.shift_pressed and _shortcut_available:
+		# Consume releases and repeats as well, so shortcuts never become input.
+		get_viewport().set_input_as_handled()
+		if key.pressed and not key.echo:
+			activate()
+		return
+	if not is_active or not key.pressed:
+		return
+	if key.keycode == KEY_ESCAPE:
+		deactivate()
+		get_viewport().set_input_as_handled()
+	elif key.keycode == KEY_TAB and not key.ctrl_pressed and not key.alt_pressed and not key.meta_pressed:
+		var controls := _focusable_controls(content)
+		if not controls.is_empty():
+			var index := controls.find(get_viewport().gui_get_focus_owner())
+			var step := -1 if key.shift_pressed else 1
+			controls[posmod(index + step, controls.size())].grab_focus()
+		get_viewport().set_input_as_handled()
+
+func _focusable_controls(node: Node) -> Array[Control]:
+	var result: Array[Control] = []
+	for child in node.get_children():
+		if child is Control and child.is_visible_in_tree() and child.get_focus_mode_with_override() == Control.FOCUS_ALL:
+			if not (child is BaseButton and child.disabled):
+				result.append(child)
+		result.append_array(_focusable_controls(child))
+	return result
+
+func _on_focus_changed(control: Control) -> void:
+	if is_active and control != null and is_ancestor_of(control):
+		_last_focus = control
+	elif is_active and control != self:
+		deactivate()
+
+func _on_visibility_changed() -> void:
+	if not is_visible_in_tree():
+		deactivate()
+
+func _update_style() -> void:
+	var style_name := "panel_active" if is_active else "panel_inactive"
+	_panel.add_theme_stylebox_override("panel", get_theme_stylebox(style_name, "SurfaceSide"))
+	_refresh_header()