Re: [9fans] drawterm tearing

[Russ Cox <rsc@swtch.com>]

> scrolling does not fix the problem.  the framebuffer
> is wrong.  forcing faces to redraw does fix the problem.
> i don't have enough screen real estate so faces is sometimes
> partially obscured by acme.  the tear appears to be in line
> with the top of acme's window.  in testing just now it
> happened 4/4 times with faces partially obscured and 0/3
> times with faces not obscured.

great. now that you have a reproducible test case, try this:

in drawterm/gui-x11/x11.c:/^xdraw it says

        /*
         * drawterm was distributed for years with
         * "return 0;" right here.
         * maybe we should give up on all this?
         */

        if((dxm = dst->X) == nil)
                return 0;

try adding an unconditional "return 0;"
right there and see if the problem goes away.
if so, problem solved, or at least pinned on
some combination of the drawterm x11 code
and the new x11 server you have.
that code is trying to do a good job when
x11 is on the other end of a network connection,
but that case is getting less and less important.

russ