Comment 3 for bug 846204

i have personally never seen this crash. it could be the model is altered without the AppTreeView.clear_model being called which would reset the 'expanded_path' ...

My lazy solution is to catch any exceptions from the offending code with a 'try:' (see linked branch)

Not ideal. There is a gtk_tree_model_iter_is_valid method but the docs warn it is slow. not sure if try is much better...