This morning was one, on which most of my computers are receiving major system updates.
On the computer that acts as my Web-server, which I name ‘Phoenix’, this updated my Debian / Jessie version from 8.9 to 8.10.
On the computer which I most-recently installed, which I name ‘Plato’, this updated my Debian / Stretch version from 9.2 to 9.3 .
On both computers, this included a kernel-update. Additionally, it included an update, to the client-side X-server libraries. This posting has to do with the computer named ‘Plato’, which has kernel version ‘4.9.0-4-amd64′ now.
Previously I had blogged, that the computer named ‘Plato’ was suffering from a mysterious bug in its ‘Wayland’ compositor. If the compositing became suspended for any reason, after resuming, black rectangles would appear on the screen, as newly-opened windows faded in and out. This used to happen regardless of whether OpenGL 2 or OpenGL 3 compositing was being used.
Well since the update today, I tested the key-combination <Shift>+<Alt>+F12 again, which does the equivalent of sending the command to the compositor, to suspend. Apparently, the behavior of this key-combination has been changed since Debian / Jessie, so that instead of toggling, the compositing suspends for several seconds, and then automatically resumes. This would be useless as a user-feature, but can help with testing, because presumably, what an OpenGL application is supposed to do, is resend the signal every second or so, to make sure that compositing stays off.
To my pleasant surprise, I found that after compositing resumes, I no longer get black rectangles on the screen!