### 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
TRACKMOUSEEVENT tme;
	tme.cbSize = sizeof(TRACKMOUSEEVENT);
	tme.dwFlags = TME_LEAVE;
	tme.hwndTrack = hWnd;
	tme.dwHoverTime = HOVER_DEFAULT;
	TrackMouseEvent(&tme);
}
bool DisplayServerWindows::has_feature(Feature p_feature) const {
	switch (p_feature) {
		case FEATURE_SUBWINDOWS:
		case FEATURE_TOUCHSCREEN:
		case FEATURE_MOUSE:
		case FEATURE_MOUSE_WARP:
		case FEATURE_CLIPBOARD:
		case FEATURE_CURSOR_SHAPE:
		case FEATURE_CUSTOM_CURSOR_SHAPE:
		case FEATURE_IME:
		case FEATURE_WINDOW_TRANSPARENCY:
		case FEATURE_HIDPI:
		case FEATURE_ICON:
		case FEATURE_NATIVE_ICON:
		case FEATURE_SWAP_BUFFERS:
		case FEATURE_KEEP_SCREEN_ON:
		case FEATURE_TEXT_TO_SPEECH:
			return true;
		default:
			return false;
	}
}
String DisplayServerWindows::get_name() const {