Where is the command that is run when 'Open Link' is clicked?

[Chris Green]

On Wed, Dec 06, 2017 at 09:35:37PM +0000, Chris Green wrote:
> I want to investigate why, when I click on 'Open Link', I get a new
> instance of my browser (Vivaldi).
> 
> When I was using Firefox and clicked 'Open Link' I'd get a new tab in
> my existing browser window.  I want the same to happen with Vivaldi.
> 
> When I run Vivaldi with a URL on the command line it *does* open a
> new tab in my existing Vivaldi window so it seems strange that this
> doesn't happen when clicking 'Open Link'.
> 
> So where is the command stored that is run when one clicks 'Open Link'?
> 
Actually on looking harder I've realised that when I right click and
run 'Open Link' I get a Firefox window even though vivaldi is my
default browser.

So the question is more 'how do I *really* set my default browser to
Vivaldi'?  :-)

-- 
Chris Green