With the arrival of OS X 10.8, Mountain Lion, Apple has changed the way software updates are handled. The Mac App Store is used instead. This also means a change to the way we suppress, or hide, individual updates or show all the available updates. Here’s how to do it the old way, in Lion, and then the new way, in Mountain Lion.
OS X Lion
Up to and including OS X 10.7, “Lion,” Apple used only a preference pane to control software updates. If you click on a single entry, you can use a Menu item to suppress it from further viewing.
Hiding, In more detail, the Update Menu item says, “Ignore Update.” You’d do this of you’re tired of looking at an update that you don’t plan to use for a long time, if ever.
Lion's Software Update Pref. Pane
Click on the item, then, from the Update Menu, select “Ignore Update.” That item will never again appear in the list of available updates, but it can be recovered.
Recovery. To make all suppressed updates visible again, you use also the Software Update Menu and select “Reset Ignored Updates.”
OS X Mountain Lion
With the introduction of the Mac App Store, Apple perhaps felt that it doesn’t make sense to go to one place to update the system software and another place to update the apps. Accordingly, Mountain Lion uses the Mac App Store (MAS) for system updates. The result is that the procedure to hide one of the updates is not so obvious.
Hiding. Launch the Mac App Store from the Apple menu or the icon in the dock. At the top of the window, you'll see an entry for system software updates. If there are several, the list will be condensed. Click on “More” to see an expanded list.
Mountain Lion uses the MAS for system updates
Next, hover your mouse over the item you want to suppress and Right Click. (or CTRL + Left Click). A small box will appear that says, “Hide Update.”
Right click an item to hide it.
If the box doesn’t appear, make sure you’re logged onto the Mac App Store from the same account from which the item was acquired.
Recovery . From the Store Menu, select the item “Show All Software Updates.”
From the Store Menu, select "Show All Software Updates"
Finally, again from the Store Menu, select “Reload Page.” All the software updates you hid before will now be available. (You may have to click on More... again to see the full list.)