When I upgraded to Ubuntu 12.04 cairo-clock started acting strange. I had an icon on the left side in the bar, but when I click it, it starts a new clock every time, does not switch to it.
I removed the shortcut, but when I start cairo-clock, it continues acting the same way.
I checked these two options in cairo-clock's Properties
I was surprised, because it worked fine in all my previous Ubuntu, after upgrade. So may be the new 12.04 reset these settings, or it just needs them....