All-sides resize of borderless NSWindow in Lion

In Lion, the standard resize method for windows changed from the lower-right corner to all sides, with an invisible area to click and drag. I have a custom borderless window, similar to the App Store, on which I would like to have this resize behavior (currently, I have a custom resizer view in the开发者_开发知识库 bottom right). I searched for "10.7" in the NSWindow documentation, but none of the newly available messages seem to suggest a way to enable this.

Thanks.

I don't know which object is responsible for setting it up, but NSWindow now has tracking areas in the corners and edges (Open Quartz Debug and check "Show tracking rectangles" to see what I mean). You could emulate this behavior without too much difficulty -- it's basic geometry.