EMPTY_STACK
result = EMPTY_STACK()? (PANEL *) 0 : _nc_bottom_panel->above;
returnPanel(EMPTY_STACK()? (PANEL *) 0 : _nc_top_panel);
result = EMPTY_STACK()? (PANEL *) 0 : _nc_top_panel;
#define Is_Bottom(p) (((p) != (PANEL*)0) && !EMPTY_STACK() && (_nc_bottom_panel->above == (p)))
#define Is_Top(p) (((p) != (PANEL*)0) && !EMPTY_STACK() && (_nc_top_panel == (p)))