Program on Xcode (OS X)

You need to write a code program that when you start should display a small (about 15×15 pixels) picture from the file (the file must be in the internal resources of the project) near the mouse cursor. When moving the cursor, this picture should not lag behind it (smoothly, without brakes and without loading the system). After 20 seconds, the picture should disappear. Appearance and disappearance should be accompanied by animation, such as smooth, or as if to look out from behind the cursor, and then hide back. Other types of animation are welcome, and I can pay extra for them. While the program is running, it should not be displayed in cmd+Tab.

The earlier versions of OS X are supported, the better.

PS. I need the code, not the program. Therefore, the code should be literate, clear and with comments.