Are you getting the following error when you try to install an update to the AdBlock Mac app?

“AdBlock” cannot be updated because its extensions are in use by “Safari”. Click OK and quit the application.

The AdBlock app runs in the background, where you can't see it. You need to quit it before the App Store will install the update. But how can you quit an application you can't see? Follow these instructions from Apple Support.

To force a Mac app to quit, press Option+Commnd+Esc and select the app in the Force Quit window.