Missing fretboard orientation option

[John Sellers]

> I'm not top posting.
There is a problem with landscape orientation of a fretboard in 2.11.65.

% begin sample
 s1^\markup { 
     \fret-diagram-terse #"x;3-3;2-2;o;1-1;o;" 
     "    normal"
 }
 s1^\markup { 
     \override #'(fret-diagram-details . ( (orientation . landscape) ))
     \fret-diagram-terse #"x;3-3;2-2;o;1-1;o;" 
     "    landscape"
 }
% end sample

This is literally a matter of point of view because if a regular guitar player 
who bends his/her head forward and down to look over the instrument back at 
his/her own fretboard, the 2.11.65-landscape most closely matches what will be 
seen.

However, a very useful orientation, and perhaps, the most useful orientation is 
not allowed. 

To explain:

The Fretboard orientation allows two options: normal and landscape.

The normal view is with the nut at the top, just as if a guitar were placed in 
the same orientation of the printed Fretboard.  The 2.11.65-landscape 
orientation is similar to the 2.11.65-normal orientation rotated 90 degrees in 
the sense of a clock facing the observer.

Unfortunately the 2.11.65-landscape option produces a image that is upside down 
to how a conventional guitar play plays a conventional instrument.  You see, 
for most guitarists, a printed fretboard in 2.11.65-landscape the lowest string 
on the bottom instead of the top, thus possibly causing confusion.  On the 
other hand, a left-handed guitar player with a regular guitar would not be any 
better off with the notation since the fingerings would have to be different 
from most players.

The practice of one fine, world-class Jazz guitar player is to write the 
fretboard notation with the nut to the right. This notation would be the same 
as rotating the current landscape notation by 180 degrees about an axis 
perpendicular to the paper.  

This approach makes good sense because Jazz players often play by ear, and they 
often teach each other by showing each other new fingerings while playing.  
When the fretboard of another player is observed in this way, for almost all 
players the nut will appear to be on the observer's right, with the lowest 
string on the top.  From the standpoint of an observer of a guitar player, this 
most closely matches the before mentioned orientation of rotating the 
landscape-2.11.65 orientation 180 degrees about an axis perpendicular to the 
paper.

Such players will have long experience in interpreting another players 
fingering in exactly this orientation, and that experience would make the 
suggested orientation much easier for them to read.