Display simple box indicating position on mouse click?

[Toralf Lund <toralf procaptura com>]

In one of my applications, I'd like to display the pointer position 
(within the widget) when a certain mouse button (I haven't decided 
which) is clicked, in some kind of a popup box. Any suggestions about 
how to achieve this? I mean, to capture the actual click and get the 
position, I can probably just connect to signal_button_press_event() - 
or possibly signal_button_release_event(), but what's the best way of 
actually displaying the information? Maybe I want something rather like 
the standard tooltips, but I don't know how to force display of those...

- Toralf