How To Pass an XPCOM Object to a New Window

If you want to be able to call functions within an XPCOM object from a XUL window's code, you can do so if you pass the XPCOM object as one of the arguments to the window creation method.

For example:

var ww =
      Components.classes["@mozilla.org/embedcomp/window-watcher;1"].
            getService(Components.interfaces.nsIWindowWatcher);

var win = ww.openWindow(null,
      "chrome://myextension/content/debug.xul",
      "debug history", "chrome,centerscreen,resizable", myObject);

Note in this example that myObject is passed to the openWindow() method; you can pass any XPCOM object (or any other value, for that matter) in this way. To access the XPCOM object from the window's code, you can access the window.arguments[] array, as shown in the example below:

Components.utils.reportError(String(window.arguments[0]));

This will produce output similar to "[xpconnect wrapped nsIMyXPCOMObject]".