Comment # 5 on bug 1087741 from Simon Lees

(In reply to George Anchev from comment #3)
> Further testing:
> 
> 4. In System Settings -> Default Applications -> Web Browser set explicitly
> to open http(s) URLs in application torbrowser.
> 5. Repeat step 3 
> 
> RESULT:
> 
> Now when I click a link (e.g. in claws-mail or in console) Tor Browser
> starts (if it is not started) but does not open the URL. If it was already
> started I simply get a message box:
> 
> "Tor Browser is already running, but is not responding. To open a new
> window, you must first close the existing Tor Browser process, or restart
> your system."
> 
> and the URL still doesn't open in it.
> 
> Reported upstream:
> https://trac.torproject.org/projects/tor/ticket/25806

What you did in 4 is the correct approach for KDE, xdg-utils will look at those
settings rather then the other mimetype ones, if tor-browser is being opened
but the page isn't loaded that seems more like an issue with its handling of
command line params or its desktop file is setup to handle them wrongly,
especially if chromium and firefox will open them when they are the default.