### 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
}
			[[fallthrough]];
		}
		case WM_CHAR: {
			ERR_BREAK(key_event_pos >= KEY_EVENT_BUFFER_SIZE);
			
			KeyEvent ke;
			ke.shift = (wParam != VK_SHIFT) ? shift_mem : false;
			ke.alt = (!(wParam == VK_MENU && (uMsg == WM_KEYDOWN || uMsg == WM_SYSKEYDOWN))) ? alt_mem : false;
			ke.control = (wParam != VK_CONTROL) ? control_mem : false;
			ke.meta = meta_mem;
			ke.uMsg = uMsg;
			ke.window_id = window_id;
			if (ke.uMsg == WM_SYSKEYDOWN) {
				ke.uMsg = WM_KEYDOWN;
			}
			if (ke.uMsg == WM_SYSKEYUP) {
				ke.uMsg = WM_KEYUP;
			}
			ke.wParam = wParam;
			ke.lParam = lParam;
			key_event_buffer[key_event_pos++] = ke;
		} break;
		case WM_INPUTLANGCHANGEREQUEST: {
			
		} break;
		case WM_TOUCH: {
			BOOL bHandled = FALSE;
			UINT cInputs = LOWORD(wParam);
			PTOUCHINPUT pInputs = memnew_arr(TOUCHINPUT, cInputs);