So, when you use OS X Dashboard widgets for a while, chances are you’ll download a few of them that might fit together into categories. In OS X Mountain Lion, Apple set the “Add More Widgets” screen to look a lot like iOS, as we showed you in a previous tip. The cool thing is that you can create iOS-Style folders in here, too, and add a bunch of apps to one slot, thereby organizing your Dashboard in a similar way to that of an iOS device screen.
Put Dashboard Widgets Into iOS-Style Folders In Mountain Lion [OS X Tips]