What if you have a function which you want to be called when nothing
else is happening ?
| gint gtk_idle_add( GtkFunction function,
                   gpointer    data ); | 
This causes GTK to call the specified function whenever nothing else
is happening.
| void gtk_idle_remove( gint tag ); | 
I won't explain the meaning of the arguments as they follow very much
like the ones above. The function pointed to by the first argument to
gtk_idle_add will be called whenever the opportunity arises. As with
the others, returning FALSE will stop the idle function from being
called.