Panorama shows a random[?] thumbnail in the "group tabs"/Panorama view (see attachment) Reproduce: * Open several tabs in Firefox * Group them into at least two Panorama groups (I have only tested with at least two groups, so this might be optional) * [Might be optional] * Enable session saving * Close/Reopen Firefox * Do some of the following * Resize Firefox window (This seems to have the most impact) * Resize Panorama groups (especially make them so small that they stack, and expand again) * Click the "Expand" button on a collapsed group * Enter/Leave Panorama view (by clicking on random tabs)

Thanks for reporting! This is a duplicate of bug 659278 (which is already fixed and will be included in Fx 8 - the next Firefox release).