Re: Redisplay problems?

[Stefan <monnier@IRO.UMontreal.CA>]

> OTOH, when we need to deiconify a frame, or expose a large portion of
> it, I see no space for significant optimizations anyway.  Redisplay
> optimizations are about redrawing as small portions of the frame as
> possible.  But in the case in point, we basically need to redraw the
> entire frame -- how much can you win here anyway?

Of course, the window-system may elect to do some of this redraw on its
own by keeping a copy of the frame's last content (under X11 the
corresponding feature is called "BackingStore").  In that case we don't
need to redraw the entire frame.  We may often not need to redraw
anything at all.

IIRC this "BackingStore" option is typically disabled nowadays in X11,
so we shouldn't pay too much attention to it.  But I'm not sure how
compositing window-managers behave in this respect, since they kind of
"naturally" have a kinf of backing-store.  IOW, if we want to be serious
about this discussion, we should first get some real data from w32,
Gnome, and ns cases to see if in practice, a deiconifiy is almost always
followed by an "expose" of the frame, or not.


        Stefan