Keyboard shortcuts don't work in gnome shell

Gnome-Shell uses not Metacity Window Manager, but new Window Manager - Mutter, which uses new configuration system - dconf, while old GNOME and Ubuntu Unity interface uses old configuration system - gconf. Because of this "System Settings" -> Keyboard -> Shortcuts doesn't work on Ubuntu with GNOME3 shell :(

One Workaround

Install dconf-tools

Run dconf-editor

Look in org.gnome.desktop.wm.keybindings or org.gnome.mutter.keybindings

See Ubuntu bug #965921 for more info and workarounds.

Some useful info also can be found here: blog.sudobits.com/2011/10/12/top-10-gnome-shell-keyboard-shortcuts/

in ubuntu 12.04 gnome-shell keybindings were modified so that WindowsKey and CursorKeys now control Window Maximization and Left-/Right-Side Splitting, while moving between Activities (aka Desktops) is now controlled by Ctrl-Alt and the Up/Down Keys.

To get back to much more useful behaviour, install dconf-tools and execute these dconf commands from the shell:

dconf write /org/gnome/desktop/wm/keybindings/toggle-maximized "['<Super>Return', '<Alt>F10']"
dconf write /org/gnome/desktop/wm/keybindings/switch-to-workspace-down "['<Super>Down']"
dconf write /org/gnome/desktop/wm/keybindings/switch-to-workspace-up "['<Super>Up']"
dconf write /org/gnome/desktop/wm/keybindings/move-to-workspace-down "['<Super><Shift>Down']"
dconf write /org/gnome/desktop/wm/keybindings/move-to-workspace-up "['<Super><Shift>Up']"

You will get:

<WindowsKey>Enter  : maximize Window
<WindowsKey>Left   : Align Window to left half of monitor
<WindowsKey>Right  : Align Window to right half of monitor
<WindowsKey>Up     : go to Activity/Desktop above
<WindowsKey>Down   : go to Activity/Desktop below

Thus your Ctrl and Alt Keys are once again freed up for your applications, like they should be, and only the WindowsKey is used for Windows/Desktop management.