Warning: send_expose is deprecated since 3.22.
Very rarely-used function.
This function is used to emit an expose event on a widget. This function is not normally used directly. The only time it is used is when propagating an expose event to a windowless child widget (get_has_window is false), and that is normally done using propagate_draw.
a expose Event
return from the event signal emission (true if the event was handled)