force-objects-redraw uses apply-in-pane-process, so can be used on any process.
In the case of objects-displayer,
force-objects-redraw forces redrawing of the
of the objects-displayer and the drawing-objects and any pinboard-objects-displayer objects in the
of the objects-displayer, but does not force redraw of other pinboard-objects.
force-objects-redraw is needed when you set the
slot in any of the drawing-objects inside a hierarchy, because setting does not cause automatic redrawing.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017