overriding earlier oncommands

Hi,

I'm writing an extension and I want to bind some keys to some functions.
They work ok on other pages but on gmail I've noticed some problems.
On gmail if you have some features on the 'x' key is taken by gmail for
selecting the checkboxes
near every email you have.
I have a binding for Control-x.
When I try to do Control-x while running both gmail and my extension,the one
who has priority is
gmail,it consumes the 'x' key , it does it's stuff and my oncommand for
Control-x ends up not being
executed.
How can I override this ? Is there any way ?

Thank you,
Stefan

-- 

    Stefan Petrea
    homepage     : http://perlhobby.googlecode.com/
    mobile phone : (040) 0732070179