Middle click drag&drop variable

[Bob Farrell]

Hi,

I'm looking to write a very simple script that opens currently selected 
text (the text that middle-clicking "pastes") as a URL in a new Firefox tab.

Was wondering if anyone could tell me how I can go about accessing that 
information?  My hope is that it's an easily accessible variable but 
things are generally not as easy as one would expect, so any help would 
be appreciated.  If you could give as detailed an answer as possible to 
save me having to reply with "How do you do [basic thing you took for 
granted I would know how to do]" and wasting everyone's time that would 
be brilliant.

Thanks a lot

fluid