### 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
wd.min_pressure = int(pressure.axMin);
					wd.max_pressure = int(pressure.axMax);
				}
				AXIS orientation[3];
				if (wintab_WTInfo(WTI_DEVICES + wd.wtlc.lcDevice, DVC_ORIENTATION, &orientation)) {
					wd.tilt_supported = orientation[0].axResolution && orientation[1].axResolution;
				}
				wintab_WTEnable(wd.wtctx, true);
			} else {
				print_verbose("WinTab context creation failed.");
			}
		}
	}
}
DisplayServer::WindowID DisplayServerWindows::_create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect) {
	DWORD dwExStyle;
	DWORD dwStyle;
	_get_window_style(window_id_counter == MAIN_WINDOW_ID, (p_mode == WINDOW_MODE_FULLSCREEN || p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN), p_mode != WINDOW_MODE_EXCLUSIVE_FULLSCREEN, p_flags & WINDOW_FLAG_BORDERLESS_BIT, !(p_flags & WINDOW_FLAG_RESIZE_DISABLED_BIT), p_mode == WINDOW_MODE_MAXIMIZED, (p_flags & WINDOW_FLAG_NO_FOCUS_BIT) | (p_flags & WINDOW_FLAG_POPUP), dwStyle, dwExStyle);
	RECT WindowRect;
	WindowRect.left = p_rect.position.x;
	WindowRect.right = p_rect.position.x + p_rect.size.x;
	WindowRect.top = p_rect.position.y;
	WindowRect.bottom = p_rect.position.y + p_rect.size.y;
	int rq_screen = get_screen_from_rect(p_rect);
	if (rq_screen < 0) {
		rq_screen = get_primary_screen(); 
	}
	if (p_mode == WINDOW_MODE_FULLSCREEN || p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
		Rect2i screen_rect = Rect2i(screen_get_position(rq_screen), screen_get_size(rq_screen));
		WindowRect.left = screen_rect.position.x;