### 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
if (keep_screen_on == p_enable) {
		return;
	}
	if (p_enable) {
		const String reason = "Godot Engine running with display/window/energy_saving/keep_screen_on = true";
		Char16String reason_utf16 = reason.utf16();
		REASON_CONTEXT context;
		context.Version = POWER_REQUEST_CONTEXT_VERSION;
		context.Flags = POWER_REQUEST_CONTEXT_SIMPLE_STRING;
		context.Reason.SimpleReasonString = (LPWSTR)(reason_utf16.ptrw());
		power_request = PowerCreateRequest(&context);
		if (power_request == INVALID_HANDLE_VALUE) {
			print_error("Failed to enable screen_keep_on.");
			return;
		}
		if (PowerSetRequest(power_request, POWER_REQUEST_TYPE::PowerRequestSystemRequired) == 0) {
			print_error("Failed to request system sleep override.");
			return;
		}
		if (PowerSetRequest(power_request, POWER_REQUEST_TYPE::PowerRequestDisplayRequired) == 0) {
			print_error("Failed to request display timeout override.");
			return;
		}
	} else {
		PowerClearRequest(power_request, POWER_REQUEST_TYPE::PowerRequestSystemRequired);
		PowerClearRequest(power_request, POWER_REQUEST_TYPE::PowerRequestDisplayRequired);