[Intel-gfx] xfce panel problem with SNA, not with UXA

[Grant]

> My xfce hidden panel looks great docked to the top, bottom, or right side
> of the screen, but if it's docked to the left side it looks weird when
> unhidden if I'm using SNA.  The problem does not appear if I use UXA.
> By weird I mean the background gray color has a darker gray pattern
> running through it.  I can attach a screenshot if necessary.  Others
> have reported this on the xfce list.  Please let me know if I should
> file a bug.
>
> - Grant

Actually it looks like the problem exists for me in
xf86-video-intel-2.21.15 but not in 2.99.903.

- Grant