Take ImageOverlayItem’s scene transformation matrix into account when computing overlay frag_to_tex matrix.  This allows ImageOverlayItem to be rescaled and repositioned and for its modified position and scale to be correctly reflected in the viewport.
Take ImageOverlayItem’s scene transformation matrix into account when
computing overlay frag_to_tex matrix.  This allows ImageOverlayItem to
be rescaled and repositioned and for its modified position and scale to
be correctly reflected in the viewport.

erikhvatum/RisWidget,zpincus/RisWidget,erikhvatum/RisWidget,zpincus/RisWidget