For many years I experience a puzzling problem with rclock. I use rclock on many different slackware boxes which all feature the same slack version. rclock helps to keep ssh connections open. As my X and fvwm have a dark screen background i prefer rclock (or xlcock) to run with :

rclock -update 1 -bg black -fg blue

Now it happens that either at rclock start time or 'automagically' any time later the background and foreground color settings switch apparently for no reason so that rclock subsequently turns into a bright blue patch - which then annoyingly mimics my xbiff's mail arrival announcement. The only somewhat silly solution i have for now is to manually switch -fg and -bg each time when restarting a misbehaving rclock.

Any idea what causes this ?

ok, i found the culprit that works havoc with my rclock colors : it's the shell variable $MAIL which by default points on my machines to /var/mail/$WHOAMI. if for whatever reason this files gets modified to a non-zero size it makes rclock reverse its colors. emptying this file corrects my colourful problem...