### 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)

window.minimized = true;
				} else if (IsZoomed(hWnd)) {
					window.maximized = true;
				} else if (window_rect.position == screen_position && window_rect.size == screen_size) {
					window.fullscreen = true;
				}
				if (!window.minimized) {
					window.width = window_client_rect.size.width;
					window.height = window_client_rect.size.height;
					rect_changed = true;
				}
#if defined(VULKAN_ENABLED)
				if (context_vulkan && window.context_created) {
					
					context_vulkan->window_resize(window_id, window.width, window.height);
				}
#endif
			}
			if (!window.minimized && (!(window_pos_params->flags & SWP_NOMOVE) || window_pos_params->flags & SWP_FRAMECHANGED)) {
				window.last_pos = window_client_rect.position;
				rect_changed = true;
			}
			if (rect_changed) {
				if (!window.rect_changed_callback.is_null()) {
					Variant size = Rect2i(window.last_pos.x, window.last_pos.y, window.width, window.height);
					const Variant *args[] = { &size };
					Variant ret;
					Callable::CallError ce;
					window.rect_changed_callback.callp(args, 1, ret, ce);
				}