This is surely in the “it would be nice” rather than “must have” category, but I find the UI similarity–or maybe just the color schemes --between EF, Mail, and even the Mac Firefox window mildly confusing. I typically have two EF libraries open at once, plus the other two, and there aren’t enough visual cues to distinguish them instantly, IMHO.
I’m a big EF fan and heavy user, and admittedly I’m talking about something that would add only a few seconds per hour of efficiency; still, the thought occurs to me quite often.
