[XeTeX] why does Latin Modern Mono have some stretch and shrink with XeTeX ?

[Philip Taylor]

Ulrike Fischer wrote:
> There was once a long discussion about this xetex problem around
> here http://tug.org/pipermail/xetex/2011-February/020072.html
> It is unclear if it is engine bug and imho no one ever added
> something to the issue tracker. 
Matthew concluded by writing :

It seems clear to me that this is a bug, though I'm not sure yet whether
it's better considered as a bug in the XeTeX engine or in the fontspec
package, because it's not clear where the stretchability is being set.

It seems equally clear to me that the fault cannot lie in the fontspec package,
since it can be demonstrated with a pure XeTeX example as Jean-François
has shewn ...  Whether the fault lies in the XeTeX engine or in the font is moot,
I believe.

Philip Taylor