title: How to clear keyboard buffer from stale messages
body: <p>My WinForms application has a button. This button has accelerator key (e.g. Alt+L). When button is pressed I handle the Click event and disable UI to prevent further button clicks until processing is finished. However, when accelerator key is pressed using keyboard those keystrokes are queued and get processed as soon as UI is enabled again. I don't want this. My question is how to clear/flush keyboard buffer?</p>
  
  <p>If I use KeyPress or KeyDown to eat those characters I don't know when they have been received. I only want to suppress old/stale messages that arrived when I was still processing first Click event.</p>