Fix treeModelIterNext again
Fix treeModelIterNext again

Thanks to Robert Marlow for spotting that I'd broken it again(!)

darcs-hash:20061205104312-b4c10-c0ea486de840420aa340da5b25a6a74fa8234881.gz

thiagoarrais/gtk2hs,thiagoarrais/gtk2hs,thiagoarrais/gtk2hs