Extending Error and line number

[Robert]

Hi,

Is it possible to extend Error (for example an
IndexOutOfBoundsException) yet still keep information about line number
and filename that will be shown in the Firefox javascript console when
the error/exception is not catched?

I did take a look at the ECMAScript Language Specification section 15.11
However I don't know on what basis Firefox determines to (try to) show
the line number and filename.

Robert.