I had seen that before, but obviously didn't look at it properly! Tried the instructions but didn't follow through!!
Otherwise put the following in your ~/.gtkrc-2.0 file (create the file if it doesn't exist):
That was the bit I missed. Thanks for putting it up. Amazing what you see second time around
I'm actually using Openbox but it seems the process is the same regardless. Anyway, works fine on my system.