Created attachment 471555 [details]
Noticed this while testing bug 588657. STR:
1) navigate to about: blank
2) highlight the page, so the little orange rect is on the top of content window
3) hit alt
The orange band leaves a clipped rect in chrome where it was originally positioned.
The Inspector will be shipping in the next release of Firefox (after Firefox 4), so this does not block the Firefox 4 release.
Fixed by bug 642471.