Its expanding the icons to fit the space I've made available to it in
the (vertical) panel.  I'd prefer that each icon was the same number
of pixels, regardless of the number of icons present (like twm does).
gnome 1.4 didn't seem to have this problem.

Steps to reproduce the problem:
1. make your panel vertical
2. install a window list
3. notice that the icons vary in size so that the size the window list
occupies in the panel is constant.  With a small number of windows, notice
that the icons look absurd.