### Godot version

4.0.beta12

### System information

Windows 11, RTX 3080

### Issue description

When a Window Node is created with it's Transparent flag set to true and Project Settings --> Display --> Window --> Subwindows --> Embed Subwindows is false, the Window has a black background. By cycling the transparent flag from false and back to true again, during runtime, the window's background then becomes transparent. 

### Steps to reproduce

Attempt to create a Non-embedded Subwindow with a transparent background using the appropriate flags. 

### Minimal reproduction project

Note: this project is from Reddit user [gongpha](https://www.reddit.com/user/gongpha/) and his Reddit post [Learning a Godot 4.0 Window node](https://www.reddit.com/r/godot/comments/xr8yxn/learning_a_godot_40_window_node/)

https://github.com/gongpha/godot4-window-test
_THREAD_SAFE_METHOD_
	ERR_FAIL_INDEX(p_shape, CURSOR_MAX);
	if (cursor_shape == p_shape) {
		return;
	}
	if (mouse_mode != MOUSE_MODE_VISIBLE && mouse_mode != MOUSE_MODE_CONFINED) {
		cursor_shape = p_shape;
		return;
	}
	static const LPCTSTR win_cursors[CURSOR_MAX] = {
		IDC_ARROW,
		IDC_IBEAM,
		IDC_HAND, 
		IDC_CROSS,
		IDC_WAIT,
		IDC_APPSTARTING,
		IDC_SIZEALL,
		IDC_ARROW,
		IDC_NO,
		IDC_SIZENS,
		IDC_SIZEWE,
		IDC_SIZENESW,
		IDC_SIZENWSE,
		IDC_SIZEALL,
		IDC_SIZENS,