NSToolbarPoofAnimator is an undocumented AppKit class I found using class-dump. It is known to be present under 10.2, I haven't yet tested under earlier versions.
As you might expect, this class allows you to perform a toolbar-style "poof" animation to indicate the removal of an object.
Here is the interface to the class. Just create a new NSToolbarPoofAnimator.h file and include it in your project; the implementation is already in AppKit:
To begin the animation, just use [[[NSToolbarPoofAnimator]] runPoofAtPoint:point]. You might use this in a NSDraggingSource method when something is deleted. It appears the point parameter is ignored, as the poof is always drawn under the current mouse position.
Note: From a helpful friend working on AppKit for the Man: NSToolbarPoofAnimator does indeed respond to the NSPoint argument. Try
[[[NSClassFromString]](@"NSToolbarPoofAnimator") runPoofAtPoint:NSZeroPoint] for an example. Good luck! :)
I don't see the standard disclaimer yet. Undocumented classes are usually undocumented for a reason. This functionality might change at any time, even between 10.x.y and 10.x.y+1. If you're fine with that possibility, then rock on.
Panther provides an NSShowAnimationEffect function. You should probably use this instead of the undocumented class.