Fantastic! That really brightened up my day — thanks!

Works fine on Unix too, with v5.8.0 or later. I got a syntax error Can't modify join in character translation at - line 19, near "y/.//)" with 5.004_04 on Unix but that's probably my fault for running such an old version...

It's been ages since I messed about with this affine transformation stuff, but you've reminded me how cool they can be. Now how about one shaped like a fern?! ;-)