ALT+Tab no longer switches applications since upgrade to 18.04
Solution 1:
In the Settings > Devices > Keyboard menu, you will find a list of keyboard shortcuts. Under the Navigation section, you can find the relevant functions and their associated shortcuts, and change them as you see fit. You're looking for the one named Switch applications.
Solution 2:
Run gnome-control-center
aka the Settings application.
Remove the shortcut for Switch applications by clicking on it and deleting it with the backspace key, now press the Set button.
Now set Switch windows by clicking on it, then press Alt + Tab and click the Set button.
Solution 3:
Turns out the configuration just needs to be updated in settings.
Open Settings > Devices > Keyboard and under Keyboard Shortcuts select Switch applications and update it with left Alt+Tab.
Both Alt+Tab combinations should now work.
Solution 4:
If my understanding of the problem stated here is correct try the following solution. It is a three stage process
Stage-1:
(1) Open Settings > Devices > Keyboard and under Keyboard Shortcuts
(2) Remove the shortcut for Switch applications by clicking on it and deleting it with the Backspace Key, now press the Set button.
(3) Remove the shortcut for Switch windos directly by clicking on it and deleting it with the Backspace Key, now press the Set button.
Stage-2:
(1) Create a new shortcut for Switch applications by clicking on it and then press Alt + Esc and click the Set button.
(2) Create a new shortcut for Switch windos directly by clicking on it and then press Super + Tab and click the Set button.
What we have achieved so far is simply swapping the key combinations for the following actions
Switch applications and Switch windos directly
Now let us proceed to the next stage
Stage-3:
(1) Create a new shortcut for Switch windos by clicking on it and then press Alt + Tab and click the Set button.
Voila
You have restored the behavior of ALT + TAB Key to what is required in this post.
If for any reason things are not working you can execute the steps in Stage-0 (mentioned below) and then redo steps in Stage-1 and Stage-2
Stage-0:
(1) **Open Settings > Devices > Keyboard**
(2) In the top of the screen you can see the Reset All... button and then click it
(3) It will ask for confirmation. Click Reset All
Caution: TL;DR
The steps in this stage will remove any key customization you might have done in the past before you following the steps in this thread
That's all folks
Have a great time playing with keyboard shortcuts
Solution 5:
It is also possible to use Alt + Esc
Somehow maintainers think that this is better. However I always enable Alt + Tab