A modifier key is a key that when held in combination with another key, causes a unique behavior. For example, Command-c copies highlighted data to your clipboard. The Finder modifier keys are pretty well documented. But a number of menu items support modifier keys as well. For example: Click on the Dropbox item in your menu, you’ll be able to see the status of files that have sync’d as well as a cogwheel with the typical settings for an app like Dropbox. Option-click on the Dropbox menu item, you’ll see the items under the cogwheel menu. Option-click the Wi-Fi menu item to see extended Wi-Fi information. Option-click Bluetooth, you’ll see version and…