Coming from the Windows world, I’m used to switching applications by using Command ⌘ + Tab. If this is your way of working too, you may have experienced the issue when this wouldn’t work anymore. Pressing ⌘ + Tab simply does nothing and there seems to be no way of getting it to work again. Previously, I resorted to rebooting my Mac. Now I know better.
The Application Switcher is in fact controlled by the Dock. You might see the above effect accompanied by the Dock not responding to mouseovers anymore. If you have the Dock’s magnification feature switched on, mousing over the icons does not trigger it.
Restart Dock with Activity Monitor
The simple thing to do in this case, is to restart the Dock. There’s no immediately obvious way of doing this, since the Dock has no menu of its own that would let you quit it. What you need to do is launch Activity Monitor, select the Dock process and simply force-quit it. The Dock is configured so that it automatically restarts if it is quit.
If you’ve never used Activity Monitor before, here’s how to do it:
- Open a Finder window and navigate to Applications → Utilities.
- Find the application named Activity Monitor and launch it.
- In the list, find an entry with the text Dock in the column Process Name.
- Click on that entry and select Quit Process from the View menu.
- In the popup dialog that appears, select Force Quit.
- The Dock will then quit and immediately restart and ⌘Tab should work again.