Double-Click a Window’s Title Bar

In El Capitan you can double-click a window’s title bar to zoom. This means it will expand the window to its maximum size, or back to its original size the second time. But you can change this functionality so double-clicking a window’s title bar will minimize instead, shrinking down into the Dock. Just go to System Preferences, Dock, and set the “Double-click a window’s title bar to” option to which one you want. Or, uncheck that option and double-clicking a window’s title bar will do nothing.