### 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
FreeLibrary(Shcore);
			}
			Shcore = (HMODULE)INVALID_HANDLE_VALUE;
		}
	}
	UINT x = 0, y = 0;
	if (hmon && (Shcore != (HMODULE)INVALID_HANDLE_VALUE)) {
		HRESULT hr = getDPIForMonitor(hmon, dpiType , &x, &y);
		if (SUCCEEDED(hr) && (x > 0) && (y > 0)) {
			dpiX = (int)x;
			dpiY = (int)y;
		}
	} else {
		static int overallX = 0, overallY = 0;
		if (overallX <= 0 || overallY <= 0) {
			HDC hdc = GetDC(nullptr);
			if (hdc) {
				overallX = GetDeviceCaps(hdc, LOGPIXELSX);
				overallY = GetDeviceCaps(hdc, LOGPIXELSY);
				ReleaseDC(nullptr, hdc);
			}
		}
		if (overallX > 0 && overallY > 0) {
			dpiX = overallX;
			dpiY = overallY;
		}
	}
	return (dpiX + dpiY) / 2;
}
static BOOL CALLBACK _MonitorEnumProcDpi(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) {