How to add a callback that will be called each time when the event queue becomes empty

[Gang Chen <gang chen cn gmail com>]

Hi everyone,

The background is that I need to update the sensitivity of UI elements when proper. I tried to do it in a low priority idle callback that is running forever. But that will cause 100% CPU usage. So I'd like to do it in a callback that is called only once each time when the event queue becomes empty. Do you have any idea? Or is there any better approach to updating UI elements?

Thanks,

Gang