GtkTooltips associates
some help text with a widget. If the user holds the
mouse pointer still over the widget for a short time, a
tooltip will appear displaying the help text. GtkTooltips can also store
some "private" text; you might use this with a GtkTipsQuery to display more
extensive help.
the section called Tooltips in the chapter
called The Main Window:
GnomeApp has more information on tooltips.
