Stephanie Fielek's Public Library

But what if you don’t want to  always  lock your screen when the screen saver activates or your computer wakes from sleep? In other words, you don’t want to set that option in the Security pane as you must for the methods I’ve described so far. (After all, it can be a pain to have to enter your password over and over again throughout the day.) Keychain Access holds the key. You can use this application (in your Applications/Utilities folder) to quickly activate your screen saver from the menubar  and  require a password to turn it off—even if the Security pane option isn’t enabled. Open Keychain Access and then go to Keychain Access: Preferences. Click on the General tab and select the Show Status in Menu Bar option. A small lock icon will appear in your menu bar. Close the Preferences window and quit Keychain Access. Now click the lock icon in your menubar and choose Lock Screen to start your screen saver.  You can even define a keyboard shortcut for the Keychain Access Lock Screen menu. First make sure the Lock Screen icon is the leftmost of your Apple-provided menubar icons. Hold down the Command key and drag the lock icon to the left edge of your existing icons, then drop the icon. This step is necessary to make this trick work. Now open System Preferences, and click on the Keyboard & Mouse pane. Click the Keyboard Shortcuts tab, and then click the plus sign to add a shortcut. Leave the pop-up menu set to All Applications, enter  Lock Screen  for the Menu Title, and then define a keyboard shortcut to use