### 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
}
	if (p_no_activate_focus) {
		r_style_ex |= WS_EX_TOPMOST | WS_EX_NOACTIVATE;
	}
	if (!p_borderless && !p_no_activate_focus) {
		r_style |= WS_VISIBLE;
	}
	r_style |= WS_CLIPCHILDREN | WS_CLIPSIBLINGS;
	r_style_ex |= WS_EX_ACCEPTFILES;
}
void DisplayServerWindows::_update_window_style(WindowID p_window, bool p_repaint) {
	_THREAD_SAFE_METHOD_
	ERR_FAIL_COND(!windows.has(p_window));
	WindowData &wd = windows[p_window];
	DWORD style = 0;
	DWORD style_ex = 0;
	_get_window_style(p_window == MAIN_WINDOW_ID, wd.fullscreen, wd.multiwindow_fs, wd.borderless, wd.resizable, wd.maximized, wd.no_focus || wd.is_popup, style, style_ex);
	SetWindowLongPtr(wd.hWnd, GWL_STYLE, style);
	SetWindowLongPtr(wd.hWnd, GWL_EXSTYLE, style_ex);
	if (icon.is_valid()) {
		set_icon(icon);
	}
	SetWindowPos(wd.hWnd, wd.always_on_top ? HWND_TOPMOST : HWND_NOTOPMOST, 0, 0, 0, 0, SWP_FRAMECHANGED | SWP_NOMOVE | SWP_NOSIZE | ((wd.no_focus || wd.is_popup) ? SWP_NOACTIVATE : 0));
	if (p_repaint) {
		RECT rect;
		GetWindowRect(wd.hWnd, &rect);
		MoveWindow(wd.hWnd, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, TRUE);
	}
}
void DisplayServerWindows::window_set_mode(WindowMode p_mode, WindowID p_window) {