An object of this class is created when a window.open() method is executed in Netscape. Within the window, the window object is visible to the scripts running inside it. From outside, the creating script is handed an EventCapturer object as a handle on the window. In MSIE, you get a genuine window object back.
The properties of the Netscape EventCapturer object are difficult to inspect because they cannot be enumerated directly. The object, like many internal objects in Netscape has a constructor which can be inspected but the object is opaque otherwise.
Because the event manager complex is so new (and somewhat fragile in Netscape 6.0) it is hard to determine whether this is still true in that version. Some work needs to be done and a revised version of Netscape will be required before this can be verified.