According to the official documentation, if you aren't implementing an item factory, you must reimplement the following:

* createEditor() returns the widget used to change data from the model and can be reimplemented to customize editing behavior.
* setEditorData() provides the widget with data to manipulate.
* updateEditorGeometry() ensures that the editor is displayed correctly with respect to the item view.
* setModelData() returns updated data to the model.

I see that you only have createEditor reimplemented.

The code ran on my desktop, so I'm not sure what else it could be. Anyways, I've made a pastie for anyone else that wants to try and help you so that they don't have to reindent the entire thing like I did.