If you have an ext2 partition that was not cleanly unmounted and
select it in ExtFSManager the Mount icon becomes active. If you
click the icon then nothing happens. You get no indication of what
might have gone wrong or why the mount failed. I was actually
even convinced that nothing had even been attempted.
It would be better if an alert dialog came up telling you the error
message that mount returned. It could also offer you the option to
fsck a filesystem if it's required.