+ is insufficient vertical space. As for <a href="@@audio-track-controls">Audio
+ tracks</a>, this can be done by either toggling the
+ track's full screen mode (<kbd class="menu">Track > Height > Fit
+ selection (Vertical)</kbd>, default : <kbd>F</kbd>, or by simply
+ double-clicking an empty space in the track header, to increase the track's
+ height.
+ <br>
+ Further, the External MIDI Device and