Ctrl+drag should not deselect (0.9.6 regression)

Steps to reproduce bug
1. Open Promenade demo
2. Single click on "Bilder einer Ausstellung" title to select it
3. Ctrl+drag title to move it

Expected behavior: Title should drag to new location

Actual behavior: Title becomes deselected on Ctrl+mouse-down. So it doesn't move anywhere.

Discussion: A normal Ctrl+click and release should deselect the item but a Ctrl+click drag and release should not deselect the item. The current behavior is confusing when selecting multiple items via Ctrl+click. For cross-references see http://musescore.org/node/4448#comment-13940

MuseScore version: r.2908

(Operating System: Windows 7)