Re: Bold by moving pixels problem

["Stefan Monnier" <monnier+gnu/emacs@flint.cs.yale.edu>]

>     That's not quite accurate.  The updating is about as immediate with
>     my synchronous signal handler as it is with the current async
>     signal handler, because it can take place any time QUIT is used,
>     which means "also in the middle of elisp code".
> 
> Please forgive my confusion.
> 
>     I've been running with synchronous signal handlers since I mentioned
>     it on this list and I'm pretty happy with it.
> 
> I think it would be good for more people to try it.

I have installed patches to that effect.
By default, nothing's changed.  But if you define SYNC_INPUT, then signal
handlers will only set a variable and the actual processing will be done
from UNBLOCK_INPUT or from QUIT, whichever occurs sooner.

Please try it out.  Normally, the only problem you might encounter with the
patch is that Emacs gets unresponsive.  If that happens, please try to
figure out how to reproduce it, and also try to get a (bunch of) C backtrace
of when the unresponsiveness happens.

I've been using a very similar patch for a while now with no problems.

If SYNC_INPUT has no ill effect, it would be good to make it the default
unconditionally.  This would allow us to get rid of the ugly BLOCK_INPUT
wrappers in alloc.c, for one thing.  It would also make Emacs more stable by
removing a whole class of hard to reproduce bugs (we've squashed some of
those over time, but as the recent mallopt problem showed, there are still
several lurking).


        Stefan