WinList widget
&xcenter; gives the WinList widget special handling when you switch icon size.
Because WinList can set its icon size independently, &xcenter; only changes that
widget's icon size if it was the same as XCenter's at startup. If it was different,
&xcenter; will leave its size alone. This lets you change your mind about &xcenter;'s
icon size without having to restore WinList's setting each time.