I am also using Linux (yet Ubuntu hardy) with firefox and played
around with mouse guestures.
If you always see a context menu upon right click, drag do the
following fix.
EDIT (top bar)
Prefrences
[Content]
next to "Enable JavaScript" hit Advanced
make sure "Disable or replace context menus" is checked.
Note, this frankenstein patch approach does open up risks from other
malicious (or candid idiot) sites.
They too will be able to disable the context menu by javascript.
<possible fix in firefox>
allow users to set options on a per URL basis
or make trusted and untrusted sites, with different security options.