I just wasted an enormous amount of time trying to figure out why I could no longer use shortcuts (like Alt-B for bold or Alt-A for links) within the quicktags editor of WordPress. I recently upgrade to FireFox 2.0 and that's when the problem started. I found a solution and wanted to share here in the hopes that some other poor soul might be saved the trouble of searching.
The forums and the wordpress site were generally not helpful. Buried deep within the bowls of this WordPress codex page we learn that "Firefox 2.0b2 uses Alt-Shift" now for it's shortcuts. (Hitting Alt-B for example was displaying the bookmark menu - not exactly very helpful when ctrl-B gives you the bookmark sidebar anyway).
Using two function keys rather than one for shortcuts for far less than ideal. I finally found the solution on the Mozillazine forums:
[type in about:config to the address bar of FireFox]
ui.key.chromeAccess to 5
ui.key.contentAccess to 4
This will allow you to use Alt for webpage shortcuts and Shift-Alt for Firefox's menu shortcuts
Hope this helps someone.