Please describe the problem:
When a tooltip must be rendered on the right hand of the screen, and the text is long enough, part of it is hidden because rendered outside the screen area.
Firefox 2.x doesn't have this problem, so I assume it's a problem with Gtk+ code when positioning the tooltip.

This is a usability bug, too, since sometimes the meaning of symbols are reported only via tooltips on many sites (Launchpad "lock" icon showed in bugs you own comes to mind).

Steps to reproduce:
1. Go to a site with an image having a large enough tooltip on the right hand of the screen. For example, on 1024x768, most of Launchpad.net shows this annoying problem. Surf to: https://answers.launchpad.net/
2. Mouse hover the blue "Answers" image on the top-right corner of the browser area


Actual results:
A tooltip will appear, but it's truncated.

Expected results:
Fire up Firefox and do the same: the tooltip won't exit the browser area but it'll be moved to the left.

Does this happen every time?
Yep.

Other information: