:motion-events-without-focus

I have a toolbox window in which I would like visual feedback on hovering some (custom) buttons. But since it's a toolbox, the window itself don't usually have focus.

Is it possible to have an output-pane receive :motion events even if the interface is not the active interface? :motion-events-without-focus only seems to have effect within the active interface (at least on Cocoa).

Regards

Erik