### 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
return true;
}
void DisplayServerWindows::enable_for_stealing_focus(OS::ProcessID pid) {
	_THREAD_SAFE_METHOD_
	AllowSetForegroundWindow(pid);
}
int DisplayServerWindows::keyboard_get_layout_count() const {
	return GetKeyboardLayoutList(0, nullptr);
}
int DisplayServerWindows::keyboard_get_current_layout() const {
	HKL cur_layout = GetKeyboardLayout(0);
	int layout_count = GetKeyboardLayoutList(0, nullptr);
	HKL *layouts = (HKL *)memalloc(layout_count * sizeof(HKL));
	GetKeyboardLayoutList(layout_count, layouts);
	for (int i = 0; i < layout_count; i++) {
		if (cur_layout == layouts[i]) {
			memfree(layouts);
			return i;
		}
	}
	memfree(layouts);
	return -1;
}
void DisplayServerWindows::keyboard_set_current_layout(int p_index) {