RE: debugger with pop-up-frames non-nil: keeps creating new frames

[Drew Adams]

        And, yes, I think the default value for
        `display-buffer-reuse-frames' should
        be `t'. People upgrading from versions of Emacs that don't have this
        variable will expect more or less unchanged behavior
        without having to explicitly set this variable to `t'.

    As far as I can tell, the current default of nil provides unchanged
    behavior.  The change was in version 1.302 of windows.c.
    Why do you think it is the contrary?
    (Such a change could be an improvement nonetheless.)

It's hard for me to answer what it should be, since I'm still having the
trouble I reported. What I meant was that in Emacs 20, frames are reused
without this variable, and there is no flaky debugging behavior. Also, based
on the doc string for this variable, I believe that frame reuse was the
behavior before the variable existed. Perhaps there was an Emacs version
between Emacs 20.7 and 22 that had the reverse behavior; I don't know. In
any case, whether or not this was the behavior previously, reusing frames as
the default makes sense to me.