### 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
String id = "SYSTEM\\CurrentControlSet\\Control\\Keyboard Layouts\\" + String::num_int64((int64_t)p_layout, 16, false).lpad(8, "0");
	String ret;
	HKEY hkey;
	WCHAR layout_text[1024];
	memset(layout_text, 0, 1024 * sizeof(WCHAR));
	if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, (LPCWSTR)(id.utf16().get_data()), 0, KEY_QUERY_VALUE, &hkey) != ERROR_SUCCESS) {
		return ret;
	}
	DWORD buffer = 1024;
	DWORD vtype = REG_SZ;
	if (RegQueryValueExW(hkey, L"Layout Text", nullptr, &vtype, (LPBYTE)layout_text, &buffer) == ERROR_SUCCESS) {
		ret = String::utf16((const char16_t *)layout_text);
	}
	RegCloseKey(hkey);
	return ret;
}
String DisplayServerWindows::keyboard_get_layout_name(int p_index) const {