Create 2 wrappers for it: DIALOG_FOOTPRINT_CHOOSER and
FOOTPRINT_CHOOSER_FRAME. The first now gets called from wxGrid
editors, text button editors (such as Change Footprints), etc.
Retire FOOTPRINT_VIEWER_FRAME_MODAL. FOOTPRINT_VIEWER_FRAME still
exists, but has very few uses at this point.
Jeff Young