Changing staff type of 1.3 score to tablature retains treble clef
1. Open attached mscz (produced in 1.3).
3. Change 'Staff type' to 'Tab. 6-str. full'.
6. Choose 'MusicXML'.
8. Open MusicXML.
Result: The staff imports as a 6-line pitched staff with fingering.
Also attached is the produced MusicXML.
It only seems to apply to 1.3 scores.
Using MuseScore 2.0 Nightly Build d952c4c - Mac 10.7.5.