When dataChanged() is emitted with indexes indicating a range, then the whole viewport will be updated

When dataChanged() is emitted with indexes indicating a range, then the whole viewport will be updated as the range is not taken into consideration. If only a single index is covered by the "range" indicated in the emitted signal then it only updates that index.

Attached is an example that reproduces the problem, the signal is emitted with only rows 2-3 in the range yet all of the rows are updated. The reason it shows a QListView and a QTreeView is if you change it to emit only a single index in the range, then QTreeView works correctly, whereas QListView still doesn't.