KDE [L1 ] is a desktop environment that works with many platforms. It uses the Qt toolkit by Trolltech [L2 ]
Tk_Theme [L3 ] is an extension that provides a -kdesystray option that allows you to write applications that use the KDE system tray.
[TODO write about the Tk extension that makes Tk use the Qt colors]
recently on comp.lang.tcl someone mentioned http://www.mosfet.org/liquid.html which appears to be some sort of theming engine for KDE. They were asking about a Tk like extension based on it.