Instrument name color not working

With the Inspector, if we chose a different color for an instrument name, it doesn't take it into account.

Steps to reproduce :
- Create a new score with 2 instruments
- Select one instrument and use the Inspector to change the color (ie. red).
- Unselect the instrument name, and see that the text is still black.
- Select it again, and see that in the Inspector window, the color is correct (ei. red)

GIT commit: e47d9de