In almost any mode, I can select "hidden" objects and faces by holding the mouse button down until I get a menu of selectable items at that point. This is not currently allowed when trying to assign appearances or materials. It'd be nice if this behavior were uniform throughout the program (admittedly, this may require some reworking of how appearances are assigned --- right now it's drag to the object/face, so there is no opportunity for a long mouse click. But maybe keeping the mouse steady for a second (while dragging the appearance, i.e., still holding the button) might bring up the menu?
