Ok now, this is strange. When I use the script, the window appears for a split second and then just quits. I waited for half an hour, but nothing – CPU was also on idle which I assume tells it does nothing. Look at this capture. I selected all individual objects here.

https://abload.de/img/error_tspqysnp.gif

Can you share some detail on your machine / OS you are on? Because, If it works for you, I might just use another PC/OS if necessary.

I am on x64 Win7 12GB RAM and Inkscape 0.91 latest