Although I use GNOME there are certain programmes that I use from KDE, like Kontact and konqueror and krusader. I have long had a gripe that I can’t read the tasks in Kontact because the red colouring of them obscures the text. So today I did something about it, and asked on #kde and #debian in IRC this question, "using Debian 6.0.4 and kde 4.4.5 and kontackt 2.4.7 how do I change the coloured background of tasks from red to light green or pale yellow say please?"
The answer I got wasn't a full answer to the problem, but it was enough to point me to the right place. Which is "calendar > configure calendar > colours" and then just choose your colours. Result, I can at last read the text of my tasks and see when they need to be completed by!