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Wayland Desktop features progress

This purpose of this page is to list the current missing or incomplete features in GNOME on Wayland to achieve a user experience on par with what is found on X11. But not all features listed here are equally important, there might even be some features listed which will not be implemented in Wayland eventually because they are not suitable.

This page is not meant to list known bugs or issues with existing features, nor how to debug Wayland issues, see How to debug Wayland problems for this.

It focuses primarily on GNOME because GNOME is the default desktop on Fedora Workstation, but features may need to be implemented at different levels not necessarily part of GNOME: 

* kernel: drm, evdev, etc.
* libraries: underlying libraries, e.g. libinput, libwayland, etc.
* protocol: requires a new Wayland protocol or amending an existing protocol
* Xwayland: X11 compatibility
* mutter: Wayland compositor
* gtk+: toolkit, handles client side decorations in Wayland
* apps: requires new applications

Pending

remote display

  • protocol, mutter
  • Completion: 50%

Jonas has read-only connections working well, and pointer events working somewhat.

dnd: root window drops

  • protocol, gtk+, mutter
  • Completion: 0%

We need some way to transfer drop status information to the drag source.

on-screen keyboard

  • protocol, mutter
  • Completion: 0% (TBD)

The on-screen keyboard in gnome-shell currently does not work under Wayland. That needs to be fixed as a starting point. Doing a better job on OSK requires moving away from a key event based protocol to something more like a text protocol, which is where this task overlaps with input methods.

Rui is supposed to work on this.


graphics tablet support

  • libinput, protocol, libraries, gtk+
  • Completion: 80% (TBD)

Peter and Carlos have branches for this. At least the first part of it is supposed to land in Wayland 1.10. libinput support has been merged in libinput 1.2.

A bigger missing piece here is the control-center configuration support.

clipboard proxy for xwayland

  • Xwayland
  • Completion: 50%

Copy/paste does work, kinda. There seem to be some cases where things don't manage to get from one side to the other; I (ajax) have hit cases where copying a URL from Firefox (an X11 app) into Evolution (wayland-native) doesn't do anything. I suspect that's due to getting selection type negotiation wrong. Pasting URLs from Firefox to gnome-terminal seems to work just fine, and I doubt g-t is doing any content type negotiation.

accessibility: keyboard

  • gtk+, mutter
  • Completion: 0%

Under X, key repeat and AccessX features (sticky keys, slow keys, bounce keys, toggle keys, etc) are implemented in the X server. Under Wayland, GTK+ currently implements key repeat on the client-side. There is a branch which adds the AccessX features, but implementing these client-side is not ideal, and leads to some regressions. Moving it to the compositor is not trivial, because we then need to 'neuter' the AccessX implmentation in xwayland.

accessibility: mouse

  • mutter
  • Completion: 0%

Mouse accessibility features such as hover-to-click need to be reimplemented in the compositor. In contrast to keyboard accessibility, these features are implemented outside the X server for X (in mousetweaks), so this is a bit simpler wrt to xwayland.

accessibility: visual bell

  • protocol, gtk+, mutter
  • Completion: 0%

X has bell functionality as part of its protocol. There is a GTK+ branch that implements bell functionality client-side using libcanberra. This works fine, but it does not allow us to implement the visual bell accessibility feature. For this reason, we need to add a bell protocol under Wayland and hook it up to the existing bell code in mutter (which uses libcanberra too).

accessibility: device controller

  • mutter, at-spi-core
  • Completion: 0%

Orca has a feature called 'mouse review' which relies on the at-spi-registryd deviceeventcontroller interface to 'remote control' the pointer. To provide this functionality under Wayland, mutter needs to provide a device controller interface and at-spi-registryd needs to use it. After discussing this with Jonas, this should be a D-Bus interface, it doesn't need to be a Wayland protocol.

output rotation

Support for hw rotation (as exposed by the graphics driver has landed upstream). Unfortunately, this support is less common in hw than one would think, so a software fallback is still needed.

XRandR control of Wayland outputs

  • protocol, Xwayland
  • Completion: 0% (TBD)
  • Note: There is a "read-only" XRandR support in Xwayland, but it cannot send request back to the Wayland compositor so X11 applications have no control over the output configurations.
  • See also: https://bugzilla.redhat.com/show_bug.cgi?id=1289714

[otaylor] We SHOULD NOT implement this. It's a vehicle for a game to mess up the user's system. The conceptual equivalent in Wayland is for an app to ask for it's buffer to be scaled or modeset fullscreen - and that needs to be implemented in Mutter - but I don't see providing to Xwayland apps; anything running under X11 I think just has to live with the screen's current configuration.

Device and Driver information

  • mutter, gnome-control-center
  • Completion: 0% (TBD)

We want to show the same kind of GPU information in the Details pane of gnome-control-center that we get from GL_RENDERER under X11; currently, it just says "Wayland" there. I'm not entirely sure why this isn't done, glGetString(GL_RENDERER) works just fine under EGL.

One thing we may want to do is show that result for both EGL and GLX contexts, since they may differ.

See https://bugzilla.gnome.org/show_bug.cgi?id=756914 for the discussion, and for why GL_RENDERER is not sufficient.

screensaver control

Not sure that anything is needed here. GNOME has been doing screensaver control entirely over D-Bus for many years.

Xfree86-VidModeExtension in Xwayland

XVideo extension in Xwayland

  • Xwayland
  • Completion: 75%

Technically the extension is present, but no adaptors are exposed. This should be wired up to the subsurface protocol if possible.

Initial implementation by Olivier has landed.

Optional surface IDs

  • protocol, gtk+, mutter
  • Completion: 50%

This will be useful for xdg-app portals, so the portal can place dialogs relative to application surfaces. Jonas has a protocol proposal and an implementation.

Hotplug USB devices

  • mutter
  • Completion: 0%

The DisplayLink USB2 devices work under X now when hotplugged as an extra screen. These should remain working under wayland.

Outputs on secondary GPUs

  • mutter
  • Completion: 0%

Laptops where the external outputs are only connected to a secondary GPU needs to be supported in some form. These work under X currently using reverse prime.


Remove X11 requirement in mutter

  • mutter
  • Completion: 0%

Quoting Owen in upstream bug 759538: Currently, mutter will start Xwayland at startup unconditionally because it still depends on "X11 backend to GTK+ for various things within Mutter and GNOME Shell, such as theme drawing and input methods. I think we'd need to eliminate the use of GTK+ for input methods, then have some no-backend mode to use GTK+ for theme drawing without actually opening a connection to a display server".

Presenting windows

  • protocol, gtk+, mutter
  • Completion: 0%

We need some way to implement gtk_window_present(), which applications reply on.

Complete

Recording screencast

  • mutter, apps
  • Completion: 100%

Not sure what's missing here, unless you want to define a Wayland protocol for this. Recording screencasts using gnome-shell's D-Bus api works just fine today in a Wayland session.

Live screencasts using third-party applications (such as video meeting or screen sharing from a web browser) are out of scope for this feature, and rather fall under "remote display".


dnd actions

  • gtk+, mutter, xwayland
  • Completion: 100%

Carlos has a protocol proposal, and working implementations.
See https://bugzilla.gnome.org/show_bug.cgi?id=755625

Protocol additions for this have been merged. Mutter implementation of wl_data_offer v3 has been merged. GTK+ support for this has been merged too.


kinetic scrolling

  • gtk+, mutter
  • Completion: 100%

Peter has a protocol proposal and a working implementation.
See https://bugzilla.gnome.org/show_bug.cgi?id=756729

The Wayland protocol additions (pointer axis, etc) have landed. The mutter implementation has landed. The GTK+ support has landed upstream as well.


relative/locking pointer confinement

Jonas has a protocol and implementations. Will land in Wayland 1.10.
See https://bugzilla.gnome.org/show_bug.cgi?id=744104

Merged in mutter 3.19.90

hi-dpi support

  • protocol, gtk+, mutter
  • Completion: 100%

This should be complete, modulo bugs. Some additional discussions around this topic in upstream bug 93315

BLOCKER: startup notification

  • protocol, libraries, gtk+, mutter
  • Completion: 100% (TBD)

Carlos has branches with a minimal implementation that adds a new request to the private gtk-shell interface between gtk+ and mutter.

This work has been merged for 3.19.91

touch proxy for xwayland

  • protocol, gtk+, mutter, Xwayland
  • Completion: 100%

This should be complete, modulo bugs.

BLOCKER: primary selection

Lyude has a protocol suggestion and a working weston implementation.
See http://lists.freedesktop.org/archives/wayland-devel/2015-December/026084.html for the protocol.

Carlos has taken this over; he has mutter and gtk+ branches, and is now trying to finalize an agreed-on protocol. The branches have been merged now (including xwayland). Proper wayland protocol upstreaming is still pending


input methods

  • protocol, gtk+, mutter
  • Completion: 100%

The default input method setup in GTK+ is entirely client-side (display server send key events, the ibus module sends them over D-Bus to IBus...). This basically works under Wayland as it does under X, with the one exception that there is a problem with the placement of the candidate window. Rui is going to fix this for 3.19.90 [1]

accessibility: screen reader

  • Completion: 90%

Screen reading (orca) works more or less the same as under X: all the accessibility traffic goes over D-Bus (the a11y bus, to be precise). One part that doesn't work is what orca calls 'mouse review', since it relies on the device event controller functionality of at-spi-registryd.

Other dnd features

  • gtk+, mutter
  • Completion: 100%

Need to complete support for

  • Drag icons (DONE)
  • Hotspots (DONE)
  • Reliable drag end determination (DONE)
  • Cancel animation (DONE)

Protocol additions for drag end and cancel animation have been merged.

attached modal dialogs

I believe this was fixed in upstream bug 745720

For transients without parent, there is upstream bug 759161

GTK+ now has reasonable support for this. Applications need to set transient parents on their dialogs and popups.


Dropped

Window size hints

  • protocol
  • Completion: 0%

The wayland shell protocols lack the equivalent of ICCCM's WM_NORMAL_HINTS. The resize increment is particularly useful for terminal emulators, which have to resize with character cell granularity. Mutter will display this information when resizing an X window, so this works for xterm, but not for gnome-terminal.

We've just removed resize increments from GTK+, I don't think this should be added to Wayland.

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