### 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
ERR_FAIL_COND_V(!windows.has(p_window), 0);
	switch (p_handle_type) {
		case DISPLAY_HANDLE: {
			return 0; 
		}
		case WINDOW_HANDLE: {
			return (int64_t)windows[p_window].hWnd;
		}
#if defined(GLES3_ENABLED)
		case WINDOW_VIEW: {
			if (gl_manager) {
				return (int64_t)gl_manager->get_hdc(p_window);
			}
			return 0;
		}
		case OPENGL_CONTEXT: {
			if (gl_manager) {
				return (int64_t)gl_manager->get_hglrc(p_window);
			}
			return 0;
		}
#endif
		default: {
			return 0;
		}
	}
}
void DisplayServerWindows::window_attach_instance_id(ObjectID p_instance, WindowID p_window) {