Swap GUD fringe/margin mouse-2 and mouse-3 bindings

[Nick Roberts]

 > IMO, we should swap "toggle enable/disable breakpoint" (on mouse-3)
 > and "run until" (on mouse-2).  
 > 
 > In normal bindings, mouse-3 is "extend region until click position",
 > so it resembles "execute until click position".

I tend to feel that mouse-3 should pop up a menu.

 > Likewise, mouse-2 normally is "yank at point", which resembles "toggle
 > at point".

I'm not sure what "toggle at point" means, but using mouse-2 to toggle
a breakpoint doesn't seem intuitive to me.

How about putting it on C-mouse-1?  Because:

1) It's related to setting/clearing a breakpoint (on mouse-1).
2) The poor souls mentioned below can still use it.

 > I guess that "run until" is used more frequently that "enable/disable
 > breakpoint", so let's make it easier to use "run until" for the poor
 > soles with a two-button mouse (e.g. most laptop users).

I think frequency of use is a more compelling reason to put it on mouse-3.
There's another command (not documented), gdb-mouse-jump, which allows you
to jump *backwards* so that you can go over the same code again
(to be used with caution).  This is currently on C-mouse-2, and I would
move that to C-mouse-3.

-- 
Nick                                           http://www.inet.net.nz/~nickrob