This is an odd issue. I have done lots of debugging to try to figure out what is actually occurring but I have not figured it out.
This is an issue in Firefox, Internet Explorer handles the events perfectly. I have not tried any other browser.
I am not sure if this is an issue somewhere in the synchronous code, or if there is a Firefox setting I am unaware of such as a event timeout, or a Firefox bug.
Screen Capture video: http://dl.dropbox.com/u/5126043/ScreenCapture_11-7-2012%201.38.52%20PM.wmv
Steps to reproduce:
1. Bring up Firebug
2. Click in the first textarea, an async request is fired, no issue ever happens
3. Click in the second textarea, a sync request is fired, notice if the sync ajax request takes ~70ish ms to respond the next click out of the textarea will not trigger, else there is no issue
I added the link to the video because I understand the issue is rather odd and it may be confusion follow the steps to reproduce, I am hoping that with both it will be easy to reproduce.
Thanks for looking,