[OS X Emacs] Aquamacs 1.9 intermittent problems with command-C

[David Reitter]

On Oct 21, 2009, at 7:49 PM, Tom Van Vleck wrote:
>
> highlight it... so maybe the problem is that dragging over
> a region with the mouse sometimes highlights it but does not
> actually delineate the region in a way that can be copied.

Yes, that is possible.
You could take a look at the function `mouse-set-region', which  
handles that.  Look it up with C-c h f and go to its source code  
(click on source file name).  Use the Emacs Lisp Debugger (Tools menu)  
to instrument the function and take a look why it doesn't copy the  
region.