Ghost note in TAB does not toggle

Context: latest github commit sources self-compiled under Linux Mint 17, with Qt Lib 5.3 and Qt Creator 3.3.0.

Steps:

1. open or create a score with at least one TAB staff and some notes in it
2. select one note in TAB and press the "Mirror note head" command ([Shift][X] by default): the note head turns into an 'x' (so far so good)
3. press the command again

Result: nothing! The note head remains in the 'x' shape

Expected result: the note head changes back to its normal state; i.e. the "Mirror note head" command should works as a toggle (as it does for non-TAB staves) but it does not.

M.