Is there a way to check if a window is shaded?

I am trying to write a KWing Shade/Unshade roll up like effect in js.

By calling effects.windowGeometryShapeChanged I can then connect to my function, but need to know if the window is shaded or not.
In fact the most convenient would be to have a effects.windowShadeChanged signal, but unfortunately there is not.

I am a newby to KDE and programming in general, so please be gentle.

Thank you in advance.