Pressing ESC deletes all the text
CASE A
Write some stuff; Press ESC;
All the text will disappear.
CASE B
Write some stuff; Mention someone (Person-A); Write more stuff after the mentioned name; Press ESC;
The text entered after the mentioned name will disappear.
Example (with ! as the mention marker):
I love !PHP but Cobol is way more cool.
Press ESC and result will be:
I love !PHP
This is part of the default autocomplete. The keypress would need to be overridden to stop this behavior. I can look at it next time I work on this but I'm currently a little busy to get to it.
I just submitted a pull request which fixes that. It also fixes the UP and DOWN arrow keys not working in the textrea.
See bd9b3e005aaaa52da9000bdb0e5384c20583d50a for more details.
This fix doesn't work for Internet explorer. I've tested it in IE7-9 and the ESC key still deletes the text.
You can test it in this jsFiddle