In TV Combinations if you drag a channel in any of the two lists and drop it in the same or the other list, the list on which you drop the channel stops painting itself and remains blank. The items still exist, you can select them and the list works normally, but it is displayed blank.

Problem goes away only by restarting SetupTV

h4. Steps to Reproduce
1. Start SetupTV
2. Go to TV Channels -> TV Combinations
3. Click a channel on one of the lists, drag it and drop it in the left list.
4. The list gets blank.
5. Try clicking on the invisible items on the left list. The right list gets filled with the appropriate items.

h4. Additional Information
See forum thread: http://forum.team-mediaportal.com/mediaportal-1-1-0-rc-1-496/setuptv-channel-combinations-ui-problem-79726/

The bug is double-fold:
1. In MediaPortal.UserInterface.Controls.MPListView.OnDragDrop() there is a BeginUpdate()/EndUpdate() block, in which a null-ref exception may occur (targetListView is null). When this happens, EndUpdate() is not called and the list is never repainted again.we need to make sure targetListView is never null and we need to wrap the block in a try/finally construct to ensure EndUpdate() is always called.
2. In SetupTv.Sections.TVCombinations both lists have AllowDrop and AllowRowReorder set to true. Do we need these (why)? If not, setting them to false will eliminate the problem.