been using the LM9 Fluxbox RC almost since it came out and apart from the already discussed menu and volwheel problems it has been great. Really great.
Just one weird thing that I have now been seeing quite a bit: when I press Fn-F5 (on my eeepc this activates external monitor and so starts "mintfb-randr config") it seems that either X or fluxbox or both die and I end up with an old fashioned text based login / session.
The weird thing is that this seems to only happen when I have a few other applications open (e.g. firefox, openoffice, pidgin, nautilus). If I do the Fn-F5, activate external monitor, deactivate the laptop screen and press "ok" immediately after login when only my tint2 and some basic tray things are running (rednotebook, zim, wicd, dropbox, ...) then there is no problem.
PS: never had this problem with LM8 fluxbox where I used the same monitor - and I do this thing daily at least once.