Selection of multi-voice measures

Steps to reproduce bug
1. Open "adeste.mscx" demo
2. Click to select first note of treble staff
3. Shift+Click to extend the selection to the unison "E" in the second complete measure

Expected behavior: Pickup measure and the first two complete measures should be selected

Actual behavior: Whole treble staff is selected

Discussion: This seems to happen if the first note you select is voice 1 and the second note you Shift+click is voice 2

MuseScore version: r. 2717 nightly

(Operating System: Windows XP)

first reported by Xavierjazz: http://musescore.org/node/4539