Hi,
Thanks for the answer.
Look for a package called gtk-qt-engine, or something like that.
According to my package manager gtk-qt-engine isn't installed.
If I login using XFCE instead of TDE, then the problem goes away, so this is definitely related to something that's activated by using TDE.
(I'm assuming that "non-TDE apps" means "GTK applications".)
I haven't checked many apps to which tool kits are and are not affected, but OpenOffice, Firefox and Mageia control centre are all exhibiting the problem. The Mageia control centre is a particular problem because the alternative styles are making the scroll bar on the software manger very "jumpy". In Firefox my the standard them gets a load of thick black lines which don't look very nice.
Any other suggestions?
Thanks in advance.
Tim W