Reading X11 Window properties from Cjs?

[klangman]

Is there a better API to read X11 window properties from Cjs.

This gives an error...

         let xWindow = metaWindow.get_xwindow();
         let display = Gdk.Display.get_default();
         let gdkWindow = GdkX11.X11Window.foreign_new_for_display(display, xWindow);
         let atom = Gdk.Atom.intern("_PLANK_BACKGROUND_BLUR_REGION", false);
         let [success, type, format, data] = Gdk.property_get( 
            gdkWindow,
            "_PLANK_BACKGROUND_BLUR_REGION",
            "CARDINAL",
            0,
            9999,
            0       // P_DELETE (0 = don't delete after reading)
            );

The property_get() call gives this error:

Error: Function Gdk.property_get() cannot be called: argument 'actual_property_type' with type interface is not introspectable because it has a type not supported for (out caller-allocates)

[mtwebster]

Support for reading this property would need to be added to muffin, or just use xprop. Introspection isn't supported for that function - it does not know how to set actual_property_type.