[PATCH xserver 2/2] glx: Fix visual fbconfig matching with respect to swap method

[Thomas Hellstrom]

Hi, Fredrik,

On 09/26/2017 11:53 AM, Fredrik Höglund wrote:
> On Wednesday 06 September 2017, Thomas Hellstrom wrote:
>> For the built in visuals, we'd typically select the "best" fbconfig
>> without considering the swap method. If the client then requests a
>> specific swap method, say GLX_SWAP_COPY_OML, it may well happen that the
>> first fbconfig matching requirements would have been paired with the 32-bit
>> compositing visual, and the client would render a potentially transparent
>> window.
> Hi Thomas,
>
> Unfortunately this patch breaks GL applications that actually want the
> ARGB visual. They now end up using a visual that does not have an
> alpha channel. In addition, it breaks compositing of ARGB windows,
> at least in kwin.
>
> Fredrik
>
Yeah, this path, while IMO correct, uncover existing bug(s). (which are 
possible to trigger by other means as well),
There is a bug for this, (fdo #102806). I have a fix in the making. 
Needs some cleanup, though.

/Thomas