IceWM is a small, but powerful window manager for the X11 Window System.
IceWM is themeable. Every setting from the preferences file can be changed by a theme. This includes titlebars, borders, icons, events, the taskbar, etc. IceWM supports pixmapped and non-pixmapped themes and comes with an example theme for all the theme types (warp3, warp4, win95, motif, nice, pixmap, metal, gtk) that IceWM supports.