About this extension
I decided to write this simplest ever extension when, once again, I was unable to use my favorite custom hotkey (Close active tab on Esc key), defined with the Dorando's keyconfig extension, as keyconfig was, once again, incompatible with a regular minor firefox update (like 7.0.1 after 7.0). Fed up! I will stop depend on keyconfig for my favorite key. So I have written this (simplest ever) EscCloseTab extension.