Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
> Huh!  Indeed!  The condition "gpm < 0" is encountered all the time,

Yes, EWOULDBLOCK.  gpm==0 is eof from the server.

gpm==-1 is a protocol error as well as EWOULDBLOCK, but it might be ok
to quietly ignore that.  It probably only happens if libgpm.so and the
running daemon are incompatible versions.

I get some joy from the change below.  I think the add/delete descriptor
calls might be right, but I'm not terrifically confident.

One thing I notice not done is to turn off the gpm-mouse-mode minor mode
variable when stopping like this.  Maybe that's good enough.  It won't
stop normally, so as long as emacs doesn't abort that could be enough.
(You can M-x gpm-mouse-mode twice to toggle it back on.)