Works for me: Mozilla/5.0 (X11; Linux x86_64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 Mozilla/5.0 (X11; Linux x86_64; rv:6.0a1) Gecko/20110515 Firefox/6.0a1 Mozilla/5.0 (Windows NT 6.0; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 Mozilla/5.0 (Windows NT 6.0; rv:6.0a1) Gecko/20110514 Firefox/6.0a1 Is this a Mac only thing?
Yes, it's Mac-only. If you look on the more detailed bug you just marked as a dupe, I've noted that "The spacebar will dismiss the dialog on Windows and Linux; this is an OS X-only problem."
Hmm, I was pretty sure that on FF3.6 the spacebar didn't work as such, because of the platform convention to not focus the default button. [Tab-modal prompts pick this up through CommonDialog.jsm :: setDefaultFocus()] Seems like we should make tab-modal prompts at least consistent across platforms, though.
3.6 on OS X *did* accept the spacebar to dismiss the dialog, which I used frequently; this is definitely a change in behavior. Aside from that, though, I do agree that cross-platform consistency is good in this instance... part of the reason I use Firefox is that I'm on multiple platforms, and I enjoy having my browser consistent regardless of my current machine's operating system.
FWIW, I did encounter this bug on the Mac.
Bulk move to Toolkit::Notifications and Alerts Filter on notifications-and-alerts-component.