Some gnome applets have transparent backgrounds if put on a transparent panel (like launcher icons and the gnome foot menu); Others do not having a simple coloured (usually grey) background (like show desktop and lock screen). For this reason I have 2 panels, one coloured at the bottom for coloured icons, and one transparent at the top for transparency supporting icons. The clock applet used to appear coloured, however, it now appears transparent, but turns coloured (grey) on mouseover. IMHO it ought to be either transparent OR coloured on both mouseover and mouseout. Ideally it ought to be coloured all the time as it's unreadable at present, and one must mouseover to turn it coloured and thus check the time. This seems to be a silly bug that has crept in and out to be fixed upstream. Reproducible: Always Steps to Reproduce: 1. 2. 3.
This should be filed upstream at bugs.gnome.org for discussion on the proper behavior of transparent applets. Can you file a bug there and then put the link in this bug?
Done. Bug is here: http://bugs.gnome.org/show_bug.cgi?id=163536
Thanks for the report, we will watch the bug as well.