title: Changing the cursor when hovering a Gtk::Image
body: <p>I've implemented a "clickable" Gtk::Image in my application by wrapping it in a Gtk::EventBox and watching for the button-press-event.</p>
  
  <p>I now want to make the mouse cursor change to a hand when the image is hovered, but I can't find a way to do it. I attempted to use get_window()->set_cursor(). But both the Gtk::Image and Gtk::EventBox return a null pointer (which probably isn't that surprising).</p>
  
  <p>How can I change the cursor while the image is hovered?</p>