Tooltips are the messages that appear next to a widget
when the mouse pointer is held over it for a short amount of time.
They are set via the set_tip()
method.
They are especially helpful for adding more verbose
descriptions of things such as buttons in a toolbar.
This widget holds tooltips for other widgets. You should only need one
Tooltip widget for all widgets you wish to add tips to.
Tooltips can only be used on widgets which have their own x window.
Other widgets, e.g. GtkLabels can be added to an
GtkEventBox to benefit from tooltips.
