So, you're tapping your manifesto into a Macbook, but twitter, RSS and email alerts keep clamoring in your face. How to finish that latest screed with such distractions? In the "where has this been all my life?" category, a new update to OS X Mountain Lion Preview 3 has a Do Not Disturb option, which stonewalls all notifications and banners. The feature, which could be useful on plenty of other devices too, can be armed with a mouse click on the menu bar or a left swipe on a trackpad. Some other iOS-style tweaks debuted in Preview 3 include the Game Center, Notes, Airplay Mirroring and Reminders. Now, back to fomenting that revolution.