text jumps in firefox

Binary package hint: firefox

When selecting text on a web-page, the selected text sometimes (as often as on 50% page loads) shifts 1-2pixels up/down and/or left/right. Sometimes the whole selection shifts, sometimes it's only one letter on the edge of current selection, sometimes both. Inline images are also affected. Text/icon on bookmarks bar is also affected. Some GUI elements (drop-down button to the right of address field, the search-engine-select drop-down button to the left of the search field) are affected.

This is very annoying! I noticed this with Gusty only.
firefox 2.0.0.6+2-0ubuntu3
firefox-gnome-spport 2.0.0.6+2-0ubuntu3
kernel 2.6.22.10-generic

I can try to make screenshots if necessary.