Hey-- idea was not to flush the event queue, but to check if it had been flushed.
It was for an axes-limits listener callback, which plotted a different amount of data depending on the axes limits. Problem was a ton of functions (xlabel, label, title, etc..) slightly reset the axes limits, causing the callback to execute and the data to be recomputed like 20 times before the plot was even shown.
Ended up using sort of a hack to get around it with dbstack, only letting it through if the parent function was pan or zoom.
So, still an open question, and possibly a feature addition- how do you check the event queue?