This appears to be a bug in Compiz (Unity's window manager), in that the Alt+` shortcuts should appear in its shortcut list, but instead they show as disabled.
To disable (or change) the Alt+` and Alt+Shift+` to switch between multiple windows of one application:
Click here to install the Compiz Settings Manager (CCSM) using the Software Center
- Or install it from the terminal with
sudo apt-get install compizconfig-settings-manager from the terminal
Start it from the Dash or by typing
ccsm from the terminal.
Statutory Warning: Compiz Config Settings Manager is an advanced tool and one tiny mistake, typo or an accidental click of the mouse can leave your desktop unusable, requiring time and effort to fix it. Please be very careful and follow instructions...thanks. If you mess up, please see this answer on how to fix things.
Type "Unity" in the filter box on the left, and click on the Ubuntu Unity Plugin:
Click on the Switcher Tab on top, and
- Look for the Key to flip through windows in the switcher entry near the bottom (scroll down if necessary)
- Click on the Disabled button next to it
- Check the Enabled box on the "Edit Key" popup
- The keys will show, and click on the Grab key combination button
- Press any keyboard shortcut combination (it doesn't matter, unless you want to remap this behavior to another shortcut); this will appear beneath the box.
- Click on OK, and this shortcut will now show in place of the Disabled button
- Now click this button again, uncheck the Enabled box, and click on OK so that the shortcut again shows Disabled.
The Alt+` is now disabled. To also disable the reverse Alt+Shift+` shortcut, repeat step 4 for the Key to flip through windows in the switcher entry.
Finally, close CCSM and if you no longer need it, please consider uninstalling it.