### 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
SHC_PROCESS_DPI_UNAWARE = 0,
	SHC_PROCESS_SYSTEM_DPI_AWARE = 1,
	SHC_PROCESS_PER_MONITOR_DPI_AWARE = 2
} SHC_PROCESS_DPI_AWARENESS;
bool DisplayServerWindows::is_dark_mode_supported() const {
	return ux_theme_available;
}
bool DisplayServerWindows::is_dark_mode() const {
	return ux_theme_available && ShouldAppsUseDarkMode();
}
Color DisplayServerWindows::get_accent_color() const {
	if (!ux_theme_available) {
		return Color(0, 0, 0, 0);
	}
	int argb = GetImmersiveColorFromColorSetEx((UINT)GetImmersiveUserColorSetPreference(false, false), GetImmersiveColorTypeFromName(L"ImmersiveSystemAccent"), false, 0);
	return Color((argb & 0xFF) / 255.f, ((argb & 0xFF00) >> 8) / 255.f, ((argb & 0xFF0000) >> 16) / 255.f, ((argb & 0xFF000000) >> 24) / 255.f);
}
int DisplayServerWindows::tablet_get_driver_count() const {