Comment 1 for bug 539204

I took a look at this yesterday, but I'm not entirely sure yet why it is breaking. I've removed the clear() call on the combobox, which gets rid of the error, but leaves a third cellrender packed in the comboboxentry. I have no idea where that is coming from, but reusing it instead of packing the first cellrenderer gives the intended behavior. That said, I intend to get to the bottom of this and fix it properly.