Since my last post quite some progress has been made in getting KWin working on top of a Wayland compositor. My main focus of work has been on the input stack. This is something I am not really familiar with as so far we did not have to care about it.
As some might know input handling in X11 is very insecure. Every application is able to listen to every key event. And in the KDE workspaces we obviously make use of these “features”. For example the global shortcut handling is implemented as a kded module listening to all key events and notifying the application via D-Bus that the shortcut got triggered. In a post-X11 world this will not work any more: applications are no longer able to listen to all key events.
One of the important tasks therefore is to not send all input events to the
X-Server but just to the window which should get it, or to handle the input events inside KWin and discard them without passing to the applications. My current branch already supports activating screen edges and using fullscreen effects like Present Windows completely without passing the input events through X. This means that some of the longstanding issues are automatically resolved. We no longer “steal” the screen edges from applications and starting the screen locker should be possible even if present windows is active (not tested and still needs some screen locker support in KWin).
But this also means that features like the global shortcut handling start to break. Mostly because kded is not listening on my virtual X but that’s just detail 😉 So I also had to start working on global shortcut support inside KWin – otherwise I would have had a hard time to use some of the important features like switching desktops or using Alt+Tab. At the moment the latest code only supports KWin’s internal shortcuts, but global support for kglobalacceld will have to follow. We had some ideas on how to improve global shortcut handling in general anyway.
When the infrastructure was in place I couldn’t resist the temptation to work on features which had been requested for a long time and were not really possible to do with X11 (or only with huge hacks): mouse shortcuts. Ctrl+Alt+left click activates desktop cube. But that’s not enough. While sitting in the Kubuntu Developer Summit I added also mouse wheel support which allows us to ctrl+alt+wheel to switch desktops and also to use the zoom effect. This work can be found in branch kwin/global-shortcuts on my personal workspace clone.
I hope that we will soon have a decision on the “what’s master” discussion and I can start merging the changes in. Once this is done I plan to switch focus to the Qt 5 port and concentrate on this for the next few weeks.
Nevertheless this should not be a reason to stop the work on the Wayland efforts. There are so many small things which can be done and lots of low hanging fruit. I will try to setup a trello board with a few tasks, so that interested developers could start picking up some easy tasks and get their hands dirty. Once something is in place I’ll write another post.