### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Windows 11 22H2

### Issue description

If a focused subwindow is destroyed, DisplayServerWindows may still attempt to send mouse motion events to that window, because `last_focused_window` isn't updated until another window is focused.

```
ERROR: Condition "!windows.has(p_window)" is true. Returning: Point2i()
   at: window_get_position (platform/windows/display_server_windows.cpp:999)
```

### Steps to reproduce

Run the MRP, click some non-Godot application window to focus it, then click the "CLOSE" button in the secondary window. This destroys the window without re-focusing the main window, so hovering the mouse over the main window will produce the error message above.

### Minimal reproduction project

[native_windows_hover.zip](https://github.com/godotengine/godot/files/10573386/native_windows_hover.zip)

_send_window_event(windows[C->get()], DisplayServerWindows::WINDOW_EVENT_CLOSE_REQUEST);
		}
		time_since_popup = OS::get_singleton()->get_ticks_msec();
		popup_list.push_back(p_window);
	}
}
void DisplayServerWindows::popup_close(WindowID p_window) {
	_THREAD_SAFE_METHOD_
	List<WindowID>::Element *E = popup_list.find(p_window);
	while (E) {
		List<WindowID>::Element *F = E->next();
		WindowID win_id = E->get();
		popup_list.erase(E);
		if (win_id != p_window) {
			
			_send_window_event(windows[win_id], DisplayServerWindows::WINDOW_EVENT_CLOSE_REQUEST);
		}
		E = F;
	}
}
LRESULT DisplayServerWindows::MouseProc(int code, WPARAM wParam, LPARAM lParam) {
	_THREAD_SAFE_METHOD_
	uint64_t delta = OS::get_singleton()->get_ticks_msec() - time_since_popup;
	if (delta > 250) {
		switch (wParam) {
			case WM_NCLBUTTONDOWN:
			case WM_NCRBUTTONDOWN:
			case WM_NCMBUTTONDOWN:
			case WM_LBUTTONDOWN:
			case WM_RBUTTONDOWN: