### 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
use_raw_input = true;
	RAWINPUTDEVICE rid[1] = {};
	rid[0].usUsagePage = 0x01;
	rid[0].usUsage = 0x02;
	rid[0].dwFlags = 0;
	if (p_target_window != INVALID_WINDOW_ID && windows.has(p_target_window)) {
		
		rid[0].hwndTarget = windows[p_target_window].hWnd;
	} else {
		
		rid[0].hwndTarget = 0;
	}
	if (RegisterRawInputDevices(rid, 1, sizeof(rid[0])) == FALSE) {
		
		use_raw_input = false;
	}
}
bool DisplayServerWindows::tts_is_speaking() const {
	ERR_FAIL_COND_V(!tts, false);
	return tts->is_speaking();
}
bool DisplayServerWindows::tts_is_paused() const {
	ERR_FAIL_COND_V(!tts, false);
	return tts->is_paused();
}
TypedArray<Dictionary> DisplayServerWindows::tts_get_voices() const {