OK, i think the "error = false" is just a capitalisation thing: should be "False". Seemed to work before though. Maybe it's a platform thing, but I'd have thought these extensions were independent of that.
As for the licence, I copied it in from the grid .py file, so I think it's the same. I'm not too bothered by that, too be honest - on Wikimedia Commons, I just relase stuff into the public domain - I'd rather people were able to use it than I get credit.
Sorry about the XML header, I forgot to put that in before I uploaded. I also saw from SAS's edits that i shouldn't put max and min parameters on booleans...obvious I suppose, but there aren't any on this extension. The next one in the pipeline has lots though - it's a bit of a monster!
Don't worry about sounding too critical, these mistakes are elementary things by me. Thanks for helping me get these out - I have no clue how all this Inkscape SVN stuff works yet, I'm still trying to hack my way around in Python! I'm new too all this (including programming in general - I've only done tacked-on computing courses at uni), so I'm grateful for your patience.