Use this for default priority event sources
Use this for high priority timeouts. This priority is never
used inside GTK+ so everything running at this priority will
be running before anything inside the toolkit.
Use this priority for resizing related stuff. It is used internally by
GTK+ to compute the sizes of widgets. This priority is higher than
Gobject::GTK_PRIORITYto avoid resizing a widget which
was just redrawn.
Use this priority for redrawing related stuff. It is used internally by
GTK+ to do pending redraws. This priority is lower than
Gobject::PRIORITY_RESIZE to avoid redrawing a widget just
before resizing (and therefore redrawing it again).
Default priority for idle functions.
Priority for very unimportant background tasks.