\twocolitem{\windowstyle{focus}}{Bitmap shown when the button has keyboard
focus but is not pressed.}
\twocolitem{\windowstyle{hover}}{Bitmap shown when the mouse is over the
-button (but it is not pressed).}
+button (but it is not pressed). Notice that if hover bitmap is not specified
+but the current platform UI uses hover images for the buttons (such as Windows
+XP or GTK+), then the focus bitmap is used for hover state as well. This makes
+it possible to set focus bitmap only to get reasonably good behaviour on all
+platforms.}
\end{twocollist}