Fix for the bug: [OPEN-342] Bug with single-click - reproducible in 1.5.1

* Fix for the following bug:

[OPEN-342] Bug with single-click - reproducible in 1.5.1
as posted in the forum at:
http://ext.ensible.com/forum/viewtopic.php?f=3&t=634

Implementation:
Handling 'keyup' event (just ESC key), so event can be created with the next click after ESC is pressed by the user when context menu is shown .

Tested the following scenarios (on windows XP):
1)  FF & Chrome -> Create event in basic.html sample after ESC key and with single click.

Noticed the following:
1) In chrome, 'keypress' and 'keydown' events aren't triggered for ESC key, whereas in FF it is triggering.