Go to google, type something in, then try to select the text by click-dragging right to left, but keep dragging until the cursor is over the Tree Style Tabs, then release.. the page will not have registered the release and if you move the cursor over the page again it will deselect what you have just selected.

Sounds like just a nuisance, and it is, but i use quick-keys with my mouse and it really messes with my workflow.