The default font on OS X appears to be known as .applesystemuifont, but this name does not appear in the font list of the TTMSFMXToolBarFontNamePicker.
I don't know how to find out the real font name corresponding to the .applesystemuifont. So I am unsure how to initialize the font name picker.
I could insert the name .applesystemuifont into the font list with something like this:
Then I could initialize the font selection in the font picker to the .applesystemuifont. Would that be a sensible approach, or is there a better way?