bug#7802: bug #7802: 24.0.50; Extraneous `mouse-3' event when do `double-mouse-3'

[Drew Adams]

OK, I see now (and remember) that this is "by design".  Further in the same node
it says:

 "When the user performs a double click, Emacs generates first an
ordinary click event, and then a double-click event.  Therefore, you
must design the command binding of the double click event to assume
that the single-click command has already run.  It must produce the
desired results of a double click, starting from the results of a
single click.

   This is convenient, if the meaning of a double click somehow "builds
on" the meaning of a single click--which is recommended user interface
design practice for double clicks."

But I don't see this as a great design.  Though it might sometimes be
"convenient" it is in general impossible to work around.

If a `mouse-3' always appears before the `double-mouse-3' that corresponds to
_what the user actually did_, then the `mouse-3' will always be handled before
the command bound to `double-mouse-3' is invoked.  So in general that command
can do nothing to undo what the `mouse-3' command did.

"Therefore, you must design the command binding of the double click event..."
means nothing in the general case.  No matter how that command or its binding is
"designed", the command is invoked too late to do anything, in general, about
what the single-click command has already done.

This is not great, IMO.