Fretboard Diagram: needs adaptation for left-hand player

In the fretboard diagram editor, the function for creating a barre line will only allow a line coming from the right side of the fretboard, as if it wore played like an ordinary right-handed guitare.
Since I play my guitare left-handed, I need a barre line coming from the left side of the fretboard.
Also, certain chords need a mid-board barre line, with top and bottom strings released; a feature which does not seem to be included in musescore2.

Dragging the mouse to create a line would be the solution, according to me.

Thank you...