Comment 37 for bug 722017

The new list needs more error checking - I have seen several crashes with
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000059
> 0x0000000100385199 in SPGradientSelector::onTreeChange ()

(no 'steps to reproduce' at the moment - I'll provide more details once I have an up-to-date debug build which includes the patch)