If you are a Mac OS X user, I would like to bring up a key combination that you can use in the latest version of the operating system, to fade dock icons in the background for hidden applications. This feature can be enabled not only using one but with multiple key combinations.
To hide applications in the background you simply have to press the Cmd+H keys at the same time to hide all open windows belonging to application. You will not be able to view them on the desktop even though they are still running in the background. To bring all of them back to viewing mode, you have to click on the application icon found in the Dock bar. I will also explain you how you can fade dock icons in the background for hidden applications a bit later on.
Another method to hide applications in the background of Mac OS X is to press the Cmd+Option+H keys to hide all other windows which do not belong to the one currently active. From there on you can opt for hiding the active application using the first command, Cmd+H. This second key combination is really useful because you can instantly get rid of any other windows not related to the project you’re working on.
This is somewhat a hidden feature in Mac OS X and which not many users are aware about. I actually think that it is available only in Mac OS X and missing in the previous versions of the operating system. By enabling this feature, you will be able to differentiate the dock icons for the hidden applications from the ones which are not hidden, or actually running for that matter.
First of all, you have to open the Terminal in Mac OS X by going to Applications and then to Utilities. Then you should type in the following command to fade dock icons in the background for hidden applications:
defaults write com.apple.Dock showhidden -bool YES
Next you should press the Enter key and after that type in another command to restart the Dock bar in Mac OS X:
Once you press enter, there you have it. You have just learned how to fade dock icons in the background for hidden applications. Just use the Cmd+H key combination to hide all windows for the active application and you should immediately notice that the icon for the application faded away in the Dock bar.
If you want to reverse the feature and not have the dock icons fade in the background for hidden applications, you can use the following command:
defaults delete com.apple.Dock showhidden
As with any other command entered in the Terminal regarding the Dock, you should always enter the killall Dock syntax as well.
Credits for the trick to fade dock icons in the background for hidden applications go to macyourself.