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            <b><a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED --- - [sna gen4] corrupt rendering (and flickering on redraw)"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=55500#c54">Comment # 54</a>
              on <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED --- - [sna gen4] corrupt rendering (and flickering on redraw)"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=55500">bug 55500</a>
              from <span class="vcard"><a class="email" href="mailto:high.entropy@web.de" title="Till Matthiesen <high.entropy@web.de>"> <span class="fn">Till Matthiesen</span></a>
</span></b>
        <pre>(In reply to <a href="show_bug.cgi?id=55500#c52">comment #52</a>)
<span class="quote">> How about: 

> diff --git a/src/sna/gen4_render.c b/src/sna/gen4_render.c
> index cc1778a..0a59681 100644
> --- a/src/sna/gen4_render.c
> +++ b/src/sna/gen4_render.c
> @@ -1895,6 +1895,9 @@ gen4_render_composite(struct sna *sna,
>         tmp->has_component_alpha = false;
>         tmp->need_magic_ca_pass = false;
>  
> +       if (!mask)
> +               mask = sna->render.white_picture;
> +
>         if (mask) {
>                 if (mask->componentAlpha && PICT_FORMAT_RGB(mask->format)) {
>                         tmp->has_component_alpha = true;</span >

Doesn't fix it, unfortunately.</pre>
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