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Revision as of 18:33, 24 January 2011 by Mclasen (talk | contribs) (Detailed Description)



Include GNOME 3


Current status

  • Targeted release: Fedora 15
  • Last updated: 2010-01-24
  • Percentage of completion: 80%

GNOME has been mostly updated to 2.91.5 in rawhide. dconf, gtk3 and yelp-xsl and other new components are in rawhide. The dbus a11y stack is now the default. gtk3 modules have been added for at-spi2-atk, PackageKit and gtk3-engines. The GNOME 3 visual appearance is being defined in the new theme packages gnome-icon-theme-symbolic and gnome-themes-standard.

Detailed Description

GNOME 3 is the next major version of the GNOME desktop. After many years of a largely unchanged GNOME 2.x experience, GNOME 3 brings a fresh look and feel with gnome-shell. There are also many changes under the surfaces, like the move from CORBA-based technologies such as GConf, Bonobo and at-spi to dbus-based successors.

The user experience of GNOME 3 is largely defined by gnome-shell, which is a compositing window manager and desktop shell. It replaces the GNOME 2 desktop shell, which consisted of metacity, gnome-panel, notification-daemon and nautilus.

Apart from pure window management, gnome-shell provides the top bar on the screen, which hosts the 'system status' area in the top right, a clock in the center, and a hot corner that switches to the so-called 'overview' mode, which provides easy access to applications and windows (and in the future, documents).

In gnome-shell, notifications are displayed in the 'messaging area' which is an automatically hiding bar at the bottom of the screen. This is also where integrated chat functionality is provided.

Since the requirements of gnome-shell on the graphics system may not be met by certain hardware / driver combinations, GNOME 3 also support as 'fallback mode' in which we run gnome-panel, metacity and notification-daemon instead of gnome-shell. Note that this mode is not a 'Classic GNOME' mode; the panel configuration will be adjusted to be similar to the shell.

The fallback will be handled automatically by gnome-session, which will detect insufficient graphics capabilities and run a different session.

Benefit to Fedora

Fedora stays in sync with upstream, and gains a modern user experience. Some long-standing problems with the CORBA-based accessibility stack will hopefully be solved as a side-effect of the move to D-Bus


  • Package new components
  • Build packages which provide gtk modules for gtk2 and gtk3 (tracked [upstream]):
    • librsvg2 (Done)
    • ibus-gtk [bug] (Done)
    • at-spi2-atk (Done)
    • PackageKit-gtk-module (Done)
  • Make GTK-using libraries parallel-installable, or port them to GTK3, or drop their GTK dependency:
    • libnotify (done, dependency now implicit)
    • gnome-desktop (done, parallel-installable gnome-desktop3)
    • libunique ([done], parallel-installable libunique3)
    • gtksourceview ([done], parallel-installable gtksourceview3)
    • webkitgtk ([done], parallel-installable webkitgtk3)
    • vte ([bug], parallel-installable vte3)
    • libwnck ([bug])
    • libmetacity-private ([bug])
    • clutter-gtk
    • libchamplain-gtk
    • gtkimageview
    • cheese-gtk
    • polkit-gtk
    • gnome-media (library has been split off as libgnome-media-profiles, ported to GTK3)
  • Switch to the dbus-based accessibility stack (Done)
  • Implement data migration for applications that are ported from GConf2 to dconf
    • done for evince
    • done for gedit
    • done for brasero
    • done for gnome-bluetooth
    • done for nautilus-sendto
    • done for gnome-color-manager
    • done for gnome-packagekit
    • done for gnome-power-manager
  • Implement fallback from the shell to gnome-panel+metacity for unsupported hardware
  • All system status indicators must use symbolic icons, others are optional
    • power (Done)
    • sound (Done)
    • bluetooth (Done)
    • updates (not a system status indicator anymore)
    • network
    • keyboard
  • Make sure applications keep working and don't run into mixed linkage against both gtk2 and gtk3 via gtk-using libraries. Currently known problems:
    • solang (uses gtk2, but needs libbrasero-burn/media which has moved to gtk3)
    • rhythmbox (the gtk3 port will be completed in time for F15)
  • Current mixed linkage problems that need to be addressed:
    • gnome-volume-control-applet
    • rhythmbox (via libbrasero-burn/media and gnome-media-profiles which are gtk3) [bug]
    • gnomeradio (via gnome-media-profiles) [bug]
    • gthumb (via libbrasero-burn) [bug]
    • emerillon (via libclutter-gtk) [bug]
    • seahorse-plugins [bug]
    • gnome-user-share [bug]
    • claws-mail-plugins (via libclutter-gtk) [bug]
    • gnome-phone-manager [bug]
    • meego-panel-devices (via libclutter-gtk)
    • meego-panel-zones (via libclutter-gtk)
    • moblin-app-installer (via libclutter-gtk)
    • tracker [bug]
  • Upgrades need to ensure that all new components of GNOME 3 get installed when upgrading from an earlier Fedora release including GNOME 2.x. This includes in particular
    • gnome-shell (handled by a gnome-panel -> gnome-shell dependency now)
    • gnome-themes-standard

How To Test

How to test basic gnome-shell functionality:

  1. Use a system with supported graphics card
  2. Log in to a GNOME session
  3. Verify that your desktop has:
    1. A black panel at the top
    2. Your name on the top right
    3. Next to it, a system status area, with icons for sound, universal access, network, battery, etc, in symbolic style
    4. in the center of the panel, a clock that brings up a calendar popup when clicked
    5. on the left, an 'Activities' item that brings up the 'overview' when clicked
    6. the top left corner of the screen also functions as a hot corner to bring up the overview
  4. Notifications (ie 'bubbles') appear centered at the bottom of the screen, and are still available afterwards in the auto-hide 'messaging area' at the bottom right

How to test the accessibility stack:

  1. Make sure at-spi2-core, at-spi2-atk, pyatspi are installed
  2. Turn accessibility support on, with the command
gsettings set org.gnome.desktop.interface accessibility false
  1. Log in again
  2. Use the 'Universal access' menu in the system status area to turn various accessibility technologies on and off
  3. Verify that accessibility technologies work as expected
  4. Bring up the Universal Access settings, and make various changes
  5. Verify that the changes take effect

How to test fallback:

  1. Use a system with supported graphics card
  2. Log in to a GNOME session
  3. Verify that you end up with gnome-shell
  4. Switch to a system with a graphics card on which we don't have 3d support (e.g. a VM)
  5. Log in to a GNOME session again
  6. Verify that you end up with the 'classic GNOME' desktop

User Experience

The user experience (on supported hardware) will be defined by gnome-shell. If graphics hardware (and/or drivers) do not support gnome-shell, GNOME 3 starts in a 'fallback mode' where we run gnome-panel and metacity instead of gnome-shell. Note that this is not a 'GNOME 2' mode, the panel configuration will be adjusted to give a similar look-and-feel to the shell.

In GNOME 3, nautilus is no longer part of the desktop shell, but just a regular application, and it is no longer started by default.

Accessibility tools will work as well as (or hopefully better than) they used to. The onscreen keyboard will no longer be gok, but caribou, which may offer a slightly different user experience.


  • gnome-shell uses clutter, which relies on 3D hardware and drivers. In F13, the shell is known to work ok with Intel and ATI graphics, and work somewhat with the nouveau driver for NVidia graphics. For F14, we want the shell to work well with all three of
    • xorg-x11-drv-ati
    • xorg-x11-drv-intel
    • xorg-x11-drv-nouveau
  • Any packages that install modules for gtk2 (such as image loaders, input methods or theme engines) need to do extra work to make their functionality available to gtk3 too.
  • The libnotify 0.7.0 version removes some APIs that were available in 0.6. All packages that use libnotify to show notification bubbles and attach them to status icons will need some (minor) updates. (mostly done in rawhide)
  • The GDesktopAppInfoLookup extension mechanism has been disabled in GIO (it is still installed to mainain API stability, but GIO now determines default handlers by looking for x-scheme-handler mimetypes (see recent xdg-list discussion about this). Only very few packages in other GTK+-based desktops are affected by this.
  • To make default applications work, applications need to add suitable x-scheme-handler entries to the mimetype field in their desktop files. (mostly done in rawhide)

Contingency Plan

If gnome-shell is not complete or stable enough, keep it experimental and use the 'fallback mode'. If there are problems with certain combinations of graphics hardware and drivers, use gnome-shell only on known good combinations, and use fallback mode everywhere else.

If the dbus-based accessibility stack is not sufficiently functional, we switch back to the CORBA-based stack.

Applications can be ported from GConf to dconf and from gtk2 to gtk3 one-by-one, so if the porting work is not complete (and it is very unlikely that it will be), we can just ship with some applications using the new technology, while others still use the old one.


Release Notes

  • Fedora 15 includes GNOME 3. It brings the first major overhaul of the GNOME user experience in 10 years.

Comments and Discussion