Re: `overlay-arrow-position' should be automatically buffer-local

[Nick Roberts]

 >    In principle, there is only one overlay-arrow-position variable,
 >    and since its value is a marker, its value includes the buffer
 >    in which it occurs.
 > 
 >    This is how e.g. gdb can easily move the overlay arrow between buffers
 >    -- just modify the global variable.  
 > 
 > gdb could use a *gud* buffer local variable.  That way multiple
 > instances of gud wouldn't steal the arrow from eachother.

Its not about multiple instances of GUD.  The overlay arrow is displayed in
the _source_ buffer, not the GUD buffer.  As execution proceeds it can move
from file to file and hence, buffer to buffer i.e it would have the same
problem as Edebug.  Incidentally, GUD does have its own overlay arrow now and
it seems to work fine.

Nick