I have reworked the sidebar code of kpresenter. Thats what I did:

o Let drag and dorp of slide in sidebar only generate an call to move the

slide, but no longer move it itself.

o Moving of slides no longer recreates all OutlineItems but moves the them

and only updates the titles of the slides in between.

All the changes together give a big speed up, as now the methods are only
called once and are more effective.