bug#11822: 24.1; emacsclient terminal mode captures escape characters as text

[Ken Raeburn <raeburn@permabit.com>]

Eli Zaretskii <eliz@gnu.org> writes:
> I'm still not following you: what do input events have to do with the
> need to redisplay or not redisplay some frame(s)?

If we don't need to update a frame, that's great. But I'm also thinking
about cases where a frame does need updating but isn't on the
currently-used display. Though for it to be important in this context,
updating text probably don't matter much(?), just cases where we
actually need to stop and wait for a reply, which probably means changes
to face definitions like updating the foreground color. Would changing
sizes for a face cause the face to be recomputed from scratch? That's
something I sometimes do with buffers that I may well have visible on
multiple displays.

Giving updates to a remote display that's not the currently-active one
lower priority than dealing with input on the active display could let
us be more responsive on the active display, but at the risk of leaving
the other display slightly out of date in occasional cases where it
might matter (a second person working at the second display at the same
time, both displays mapping to the same physical display via multiple
ssh connections, etc).

> Anyway, I think preventing frames from being unnecessarily redisplayed
> will bring larger benefits than just avoiding realization of some
> faces.

Perhaps so. I think we've got inefficiencies at multiple levels:
updating frames that don't need it; updating faces that don't need it
(on frames where something does or may need updating); redundant color
queries to a display; probably some issues around image handling. Fixing
any of them would be an improvement, but addressing more than one is
probably better still.

Ken