The reason this happens is because Eclipse switches to the front when it activates (when displaying the time or graphics). When you deactivate Eclipse, it switches back to the application you were working in. However, before it does this, it switches to the Finder. If it didn't do this, when you quit out of the application you are working in, you will find yourself in Eclipse. This is avoided when Eclipse switches to the Finder first before going back to your application. This way, when you quit the application you are working in, you will be in the Finder, and not Eclipse.