Please make QAbstractItemView::itemDelegate(index) virtual

I need to control what item delegates are used for specific indexes.

But trying to control that using setItemDelegateForRow() / setItemDelegateForColumn() does not work well enough.

Especially the row-based delegate selection does not work well for tree based views, or in combination with a sort/filter model proxy.

By allowing me to override QAbstractItemView::itemDelegate(index), I can implement the logic needed to select the proper item delegate.

My current workaround is to create a "proxy" delegate which overrides the entire delegate interface and passes the method calls on to the real delegates, based on the model index. This feels really ugly.