Mac Javascript question (oncontextmenu)

We have a web application that uses the javascript "oncontextmenu" to set
some context specific controls. It works in IE, Netscape and Firefox for
windows, as well as on at least one Mac. However, we recently had a report
from a user who could not use it on his Mac (OS X), in either Safari or IE--
instead of triggering the context controls, he got the normal "Back, View
source, etc." menu (he holds down the mouse button for this, which I believe
is the standard Mac trigger for contextmenus?).

Can anyone think of any possible avenues for debugging the problem?

Thanks!
- Kevin

Kevin wrote:
 > We have a web application that uses the javascript "oncontextmenu" to set
 > some context specific controls. It works in IE, Netscape and Firefox for
 > windows, as well as on at least one Mac. However, we recently had a report
 > from a user who could not use it on his Mac (OS X), in either Safari or IE--
 > instead of triggering the context controls, he got the normal "Back, View
 > source, etc." menu (he holds down the mouse button for this, which I believe
 > is the standard Mac trigger for contextmenus?).
 >
 > Can anyone think of any possible avenues for debugging the problem?
 >
 > Thanks!
 > - Kevin

non-standard mouse software installed?<!-- ~MESSAGE_AFTER~ -->