### 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
int layout_count = GetKeyboardLayoutList(0, nullptr);
	ERR_FAIL_INDEX(p_index, layout_count);
	HKL *layouts = (HKL *)memalloc(layout_count * sizeof(HKL));
	GetKeyboardLayoutList(layout_count, layouts);
	ActivateKeyboardLayout(layouts[p_index], KLF_SETFORPROCESS);
	memfree(layouts);
}
String DisplayServerWindows::keyboard_get_layout_language(int p_index) const {
	int layout_count = GetKeyboardLayoutList(0, nullptr);
	ERR_FAIL_INDEX_V(p_index, layout_count, "");
	HKL *layouts = (HKL *)memalloc(layout_count * sizeof(HKL));
	GetKeyboardLayoutList(layout_count, layouts);
	WCHAR buf[LOCALE_NAME_MAX_LENGTH];
	memset(buf, 0, LOCALE_NAME_MAX_LENGTH * sizeof(WCHAR));
	LCIDToLocaleName(MAKELCID(LOWORD(layouts[p_index]), SORT_DEFAULT), buf, LOCALE_NAME_MAX_LENGTH, 0);
	memfree(layouts);
	return String::utf16((const char16_t *)buf).substr(0, 2);
}
Key DisplayServerWindows::keyboard_get_keycode_from_physical(Key p_keycode) const {