If I hook an external monitor to my Linux laptop and configure it for dual head with the Gnome system tools, I do get them configured with the proper resolution and position (one to the left of the other)

The mouse pointer, however, will apparently use the greatest of the two vertical resolutions. This way, when I move up to the top border, the mouse exits the visible screen, traveling in empty space, and this is quite annoying, because you can't go to the upper panel just by going up very fast.

Is there a way of enforcing the right resolutions for the mouse, too?

Thank you