Re: Emacs flickers periodically

[Dmitry Gutov]

On 6/17/17 4:56 PM, Eli Zaretskii wrote:

> > > Actually, Emacs flickers on a TTY more frequently than in GUI frames,
> > > because certain changes on display require that the entire TTY frame
> > > be redrawn.
> >
> > Couldn't that actually be beneficial?
>
> Beneficial in what sense?  Users are generally annoyed by flickering,
> especially when most or all of the display doesn't change.

In the "eliminating bugs" sense, bugs to which you referred later. I 
can't say I have a clear idea how, except by eliminating certain 
optimizations which you refer to in bug#16621).

And also, terminal emulators might have their own display 
synchronization logic. Still, I've never tried the test cases for the 
two bugs mentioned below in the terminal. Maybe someone should do that 
and report back.

> > As long as it's never redrawn in an inconsistent state.
>
> AFAIK, Emacs never redraws display in inconsistent state (barring
> bugs, of course).

But that's the effect that the double-buffering patch brings: limiting 
redrawing to consistent states only.

So maybe those were bugs (like 12363 and 16621), but they went unfixed 
until Daniel's patch.