[EPIC] The Qt state machine abstraction was removed, code needs adaptation.

The Qt state machine abstraction was removed in 3.x. The original goal to more abstract and simplify the code could not be achieved. The qt solution was replaced by an ""in line"" implementation which is simpler and easier to maintain.
During the transition some code was commented out resulting in some state transitions currently not working. For example some drag/drop operations may not work right in some states."

The epic is used to aggregate the related issues.