[Development] Making Binary Incompatible Changes after Qt 6.0

[Kevin Kofler]

Volker Hilsheimer wrote:
> Given the scale of Qt 6.0 it’s perhaps no surprise that in spite of
> careful reviews, we are seeing the first API issues popping up, fixing of
> which would require a breakage of binary compatibility. For example:
> 
> https://bugreports.qt.io/browse/QTBUG-87465

How about just reinstating QAbstractItemModel::setSupportedDragActions 
instead? That should be binary-compatible with 6.0 and improve source-
compatibility with Qt 5 at the same time.

        Kevin Kofler