Tablature: unable to put cursor on grace note in note input mode

Ubuntu 14.04, GIT commit: 24b0bc8

1) tab staff, 4/4
2) note input mode
3) press "Shift+6 0 Right 0 /" to enter 2 half notes and a grace note on the second
4) press Left

Result: cursor will not back up to the grace note. This remains true if you navigate away and come back, leave note input mode and return, etc. The cursor will not reach or pass the grace note. It works fine outside of note input mode. But even if you select the cursor in normal mode then enter note input mode, the selection and cursor moves to the main note., So there is basically no way access grace notes on tab staves in note input mode as far as I can tell.

The problem is here:

https://github.com/musescore/MuseScore/blob/bb879a8ecec272364e5a107165f…

At the point where this code is reached, we have managed to select the grace note while leaving the note input cursor on the main note, which is the correct behavior for standard staves. But in this code, we overrule the selection of the grace note and set the selection back to a note in the main chord.

I have a tentative fix, where I check to see if a chord is currently selected and use it in preference to whatever we actually find on thie segment/track. This allows navigation to work well with grace notes, including grace note chords. Although if there is a way to actually enter a grace note chord directly, I haven't found it - I created them for testing purpsoes by copying from a standard staff.