bug#8789: 23.3; debug backtrace buffer changes window on step-through

[Michael Heerdegen]

Eli Zaretskii <eliz@gnu.org> writes:

> > > So the solution is probably to never enable `debug-on-entry' for
> > > functions that run through the mode-line mechanism.
> > 
> > That does not sound like the solution to me.

I don't see this as critical as Drew, IMHO this is not really a bug.  It
is consistent behavior, and sometimes it can useful to be able to enter
the debugger from code run by redisplaying.

But OTOH, invoking the debugger in such situations can (a) be
surprising, and even a experienced user may take some time to see what's
happening.  And, b), it is not what you want most of the time.

So, what would be cool is a user-option for that behavior.  The default
could be to not invoke the debugger from redisplay code.

A question would be how to handle similar stuff, like menu calculation,
things in pre|post-command-hook, code run by timers, etc.  I mean all
the stuff that is not run directly while processing a user command.

If such an option could easily be implemented, that would be fine.  But
if it would be too much work, I also could live without it.  I can use
`debug' to invoke the debugger directly, which prevents such surprises.


Michael.