### 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
}
		}
	} else if (IsClipboardFormatAvailable(CF_TEXT)) {
		HGLOBAL mem = GetClipboardData(CF_UNICODETEXT);
		if (mem != nullptr) {
			LPTSTR ptr = (LPTSTR)GlobalLock(mem);
			if (ptr != nullptr) {
				ret.parse_utf8((const char *)ptr);
				GlobalUnlock(mem);
			}
		}
	}
	CloseClipboard();
	return ret;
}
typedef struct {
	int count;
	int screen;
	HMONITOR monitor;
} EnumScreenData;
static BOOL CALLBACK _MonitorEnumProcPrim(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {
	EnumScreenData *data = (EnumScreenData *)dwData;
	if ((lprcMonitor->left == 0) && (lprcMonitor->top == 0)) {
		data->screen = data->count;
		return FALSE;
	}
	data->count++;
	return TRUE;
}
static BOOL CALLBACK _MonitorEnumProcScreen(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {