RE: master f51f963: Fix some side-effecting uses of make-text-button

[Drew Adams]

> > So, IIUC `make-text-button` should ideally work functionally, but for
> > historical reasons it works by side-effect.  What's the long term plan?
> > Do we plan to live with the current side-effecting behavior, or do we
> > plan to move to the "pure" functional behavior?
> 
> Given the comments in this thread it seems that there's consensus that it
> should move to the "pure" functional behavior, as the side-effecting behavior 
> is
> confusing (and this is independent of whether string literals are constant).

Please don't count me among the consenting, in
your consensus count.

> I installed the attached patch, which is along the lines that I proposed a
> couple of days ago; it has the doc fix that Pip Cet suggested.

What was the reason not to go the other direction,
and _always allow_ modification of that string arg?