This is a quick example of how to get a Transparent NSWindow using a subclassed NSWindow class and a subclassed NSView.
This is in response to a stackoverflow users request I post the source code. Which I have done here in context.
(Originally it had also had a webview which was related to the question but was not essential in any way in this example so it has been removed.)
Transparent Window with Controls and Labels overlaying it. If you click any where in the transparency the mouse will click the object behind the window. And the objects Application will become the active one.