All items from File menu do nothing

[alixdamman]

[alixdamman]

The problem lies somewhere inside the internal method _is_unsaved_modifications

[alixdamman]

The method _is_unsaved_modifications fails because self.arraywidget.dirty crashes.

[alixdamman]

Method self.arraywidget.dirty fails when it calls self.data_adapter.update_changes().

[alixdamman]

self.data_adapter.update_changes() fails because data_model.changes is None and should always exist as a dict.