copy from thegates-jam repo

ui/mouse_mode.gd

@@ -0,0 +1,39 @@
+extends Control
+
+var is_in_game: bool
+
+
+func _ready() -> void:
+	visibility_changed.connect(on_visibility_changed)
+	on_visibility_changed()
+
+
+func _input(_event: InputEvent) -> void:
+	if not is_in_game: return
+	
+	if Input.is_action_just_pressed("show_mouse"): set_captured(false)
+	if Input.is_action_just_released("show_mouse"): set_captured(true)
+
+
+func on_visibility_changed() -> void:
+	if is_visible_in_tree():
+		set_captured(true)
+		is_in_game = true
+	else:
+		set_captured(false)
+		is_in_game = false
+
+
+func _notification(what: int) -> void:
+	match what:
+		MainLoop.NOTIFICATION_APPLICATION_FOCUS_IN:
+			if is_visible_in_tree(): set_captured(true)
+		MainLoop.NOTIFICATION_APPLICATION_FOCUS_OUT:
+			pass
+
+
+func set_captured(captured: bool) -> void:
+	if captured:
+		Input.mouse_mode = Input.MOUSE_MODE_CAPTURED
+	else:
+		Input.mouse_mode = Input.MOUSE_MODE_VISIBLE