Subject: Re: bug#42406: Mouse-wheel scrolling can be flickering

From: martin rudalics <[email-masked]>
Date: Wed, 16 Dec 2020 09:46:48 +0100

>> So if Konrad sets the 'internal-border-width' frame parameter to 0 the
 >> slowdown should not happen.  Right?
 >
 > The cursor is still redrawn, so it may make no difference.

Because of the update mode lines flag?

 > The NS port has two drawing paths, on older macs and Gnustep it draws
 > and the screen is updated piecemeal. On newer macs it draws to an
 > offscreen buffer and then that buffer is drawn to the screen. Drawing
 > the buffer to the screen is very slow.
 >
 > It depends what Konrad's system is doing whether it will make much
 > difference, but I suspect he's using the off-screen buffer path so the
 > cursor redraw will force the whole frame update anyway.

Konrad says that when he suppresses setting the update mode lines flags
he sees no delays.  But apparently his cursor is still redrawn correctly
because he has seen no problems.  I'm just asking myself whether we talk
about the same problem here or only related ones.

martin