Two interesting Mac OS apps: iAlert
Both are designed to present alerts from various apps (like iTunes and Mail) in a semi-transparent, momentary window that self-dsmisses after a preferences-specified length of time (I use 2 seconds).
iAlert telling me I have (a lot of) new mail
iAlert alternate colours
So I had to disable the plugin.
Maybe I’ll try re-enabling it after I’ve caught up, but it isn’t unusual fo rme to have large amount of unread mail in mailing lists, so I would consider this a design flaw.
It should only show mail that is new since Mail started up.