### Godot version

4.0.3.stable

### System information

windows 11

### Issue description

fullscreen on the window node is not working and will show up as a windowed.

### Steps to reproduce

disable Embed Subwindows in Project Settings/Display/Window.
create a window node and set its mode to fullscreen.

### Minimal reproduction project

[fullscreen.zip](https://github.com/godotengine/godot/files/11821834/fullscreen.zip)
_THREAD_SAFE_METHOD_
	DisplayServer::WindowID window_id = _get_focused_window_or_popup();
	const WindowData &wd = windows[window_id];
	if (!wd.ime_active) {
		return Vector2i();
	}
	int cursor = ImmGetCompositionStringW(wd.im_himc, GCS_CURSORPOS, nullptr, 0);
	int32_t length = ImmGetCompositionStringW(wd.im_himc, GCS_COMPSTR, nullptr, 0);
	wchar_t *string = reinterpret_cast<wchar_t *>(memalloc(length));
	ImmGetCompositionStringW(wd.im_himc, GCS_COMPSTR, string, length);
	int32_t utf32_cursor = 0;
	for (int32_t i = 0; i < length / int32_t(sizeof(wchar_t)); i++) {
		if ((string[i] & 0xfffffc00) == 0xd800) {
			i++;
		}
		if (i < cursor) {
			utf32_cursor++;
		} else {
			break;
		}
	}
	memdelete(string);
	return Vector2i(utf32_cursor, 0);
}
String DisplayServerWindows::ime_get_text() const {