musescore/MuseScore — pull request #1590 by trig-ger (2014-12-30 08:24:46+00:00)
Title: Draw double line as a frozen columns separator in the MIDI import panel

Double line instead of single one for more contrast separation from the frozen columns
(vertical line in the middle of the picture):
https://drive.google.com/file/d/0B5alKuFoSol2UGEyYmlNTGNWLW8/view?usp=sharing