Comment 8 for bug 288236

I'm a bit concerned that this will be unexpected to some users, who won't expect that clearing "Browsing History" will clear site-specific prefs. Are we sure that the prefs being cleared are easy to recover? What if an extension sets site-specific prefs that the user went through a lot of trouble to set up? Admittedly that's unlikely to be a common scenario, but maybe we could address it by making "site specific prefs" an explicit choice in the dialog, rather than piggy-backing on "Browsing History"? Perhaps that would be overkill, as beltzner mentions.

Elmar's question should also be answered, though I don't know what the "global page zoom preference" is.