Wayland sub-surfaces is a feature that has been brewing for a long long time, and finally it has made it into Wayland core in a recent commit + the Weston commit. The design for sub-surfaces started some time in December 2012, when the task was given to me at Collabora. It went through several RFCs and was finally merged into Weston in May 2013. After that there have been only small changes if any, and sub-surfaces matured (Or was forgotten? I had other things to do.) over several months. Now it is coming out in Wayland 1.4 (plan), but what is it really?
24 May 2013
Raspberry Pi is a nice tiny computer with a relatively powerful VideoCore graphics processor, and an ARM core bolted on the side running Linux. Around October 2012 I was bringing Wayland to it, and in November the Weston rpi-backend was merged upstream. Unfortunately, somehow I did not get around to write about it. In spring 2013 I did a follow-on project on the rpi-backend for the Raspberry Pi Foundation as part of my work for Collabora. We are now really pushing Wayland forward on the Raspberry Pi, and strengthening Collabora's Wayland expertise on all fronts. In the following I will explain what I did and how the new rpi-backend for Weston works in technical terms. If you are more interested in why this was done, I refer you to the excellent post by Daniel Stone: Weston on Raspberry Pi.
3 Feb 2013
I have a Logitech DiNovo Mini (combined keyboard & touchpad), which at first worked just fine on my Gentoo laptop, Asus G50V, using the laptop's built-in bluetooth adapter, Bluez major version 4 (4.101-r5 today), and manual connection. Then I tried to connect the DiNovo to other devices, both without and with the USB-bluetooth-dongle that came with the DiNovo. Then I wanted it back to my laptop. There was a time when it worked only if I temporarily removed the battery from DiNovo. In the end, after several weeks if not months, it did not work anymore, at all. Blindly poking around, I now found how to fix it.