Prevent window moving to current workspace - how?

[Chris G]

I'm not sure if this is an xfce question or a firefox one but I'm sure
someone here will know the answer.

When I right click on a link in a (terminal) window and select "Open
Link" I don't want firfox to pop up in the current workspace, I want
the link to open in a new tab in firefox leaving firefox in the
workspace where it is curently running.  How do I get things to work
like this?  I suspect it's a Window Manager setting of some sort but
I'm not sure what it is.

-- 
Chris Green