Comment 11 for bug 279654

xrayspx (xrayspx) wrote :

You can disable this in FireFox by using about:config to set nglayout.enable_drag_images to False. This will force FireFox not to create a little image of highlighted text when you drag it, and will no longer cause KWIN to freak out and disable compositing. The fact that you're dragging will be represented by a little icon rather than a picture of what is being dragged.

A short KB article about how this feature works is here:
http://kb.mozillazine.org/Nglayout.enable_drag_images