Ctrl+Z not available in note entry mode (0.9.6 regression)

Steps to reproduce bug
1. Press "N" to begin note entry mode
2. Press a letter to add notes to the score
3. Press Ctrl+Z

Expected behavior: Note added in step 2 should disappear

Actual behavior: Nothing happens. Edit > Undo is disabled

Workaround: Use Backspace instead

MuseScore version: r. 2597. (Bug not present in 0.9.5)

(Operating System: Windows XP)