Processes all pending messages in the message queue.
void IupFlush(void); [in C] iup.Flush() [in Lua]
When you change an attribute of a certain element, the change may not take place immediately. For this update to occur faster than usual, call IupFlush after the attribute is changed.
Important: A call to this function may cause other callbacks to be processed before it returns.
In Motif, if the X server sent an event which is not yet in the event queue, after a call to IupFlush the queue might not be empty.