In the past, before this was implemented, Lua scripting did the job. And you still have complete control over the URI in the internal scripting goto-url hook. The advantages are clear - you get complete control over the URI and you can do many more interesting things with it. For example, there are some very advanced CVSweb and Debian package database URI prefixes implemented in the sample Lua hooks file. The one disadvantage to this is that you must have Lua scripting enabled in order to make use of it, and many users don't have Lua installed.