widecolor-demo: fix up summary box

src/demo/widecolor.c

@@ -8,12 +8,12 @@
 
 static int
 message(struct ncplane* n, int maxy, int maxx, int num, int total){
+  uint64_t channels = 0;
+  notcurses_fg_prep(&channels, 255, 255, 255);
   ncplane_bg_default(n);
   ncplane_cursor_move_yx(n, 3, 1);
-  ncplane_fg_rgb8(n, 0, 0, 0);
-  ncplane_bg_rgb8(n, 255, 255, 255);
   ncplane_styles_on(n, CELL_STYLE_BOLD);
-  if(ncplane_rounded_box(n, 0, 0, 5, 57, 0)){
+  if(ncplane_rounded_box(n, 0, channels, 5, 57, 0)){
     return -1;
   }
   ncplane_cursor_move_yx(n, 3, 4);
@@ -23,7 +23,7 @@ message(struct ncplane* n, int maxy, int maxx, int num, int total){
   ncplane_cursor_move_yx(n, 1, 4);
   ncplane_putegc(n, "╔", 0, 0, NULL);
   cell hl = CELL_TRIVIAL_INITIALIZER;
-  cell_load(n, &hl, "═");
+  cell_prime(n, &hl, "═", 0, channels);
   ncplane_hline(n, &hl, 15);
   cell_release(n, &hl);
   ncplane_cursor_move_yx(n, 1, 20);

src/lib/notcurses.c

@@ -1542,21 +1542,33 @@ int ncplane_box(ncplane* n, const cell* ul, const cell* ur,
   }
   ++yoff;
   // middle rows (vertical lines)
-  if(yoff < ystop - 1){
+  if(yoff < ystop){
     if(!(ctlword & NCBOXMASK_LEFT)){
       if(ncplane_cursor_move_yx(n, yoff, xoff)){
         return -1;
       }
-      if(ncplane_vline_interp(n, vl, ystop - yoff + 1, ul->channels, ll->channels) < 0){
-        return -1;
+      if((ctlword & (NCBOXGRAD_LEFT << 4u))){ // grad styling, ul->ll
+        if(ncplane_vline_interp(n, vl, ystop - yoff + 1, ul->channels, ll->channels) < 0){
+          return -1;
+        }
+      }else{
+        if(ncplane_vline(n, vl, ystop - yoff + 1) < 0){
+          return -1;
+        }
       }
     }
     if(!(ctlword & NCBOXMASK_RIGHT)){
       if(ncplane_cursor_move_yx(n, yoff, xstop)){
         return -1;
       }
-      if(ncplane_vline_interp(n, vl, ystop - yoff + 1, ur->channels, lr->channels) < 0){
-        return -1;
+      if((ctlword & (NCBOXGRAD_RIGHT << 4u))){ // grad styling, ur->lr
+        if(ncplane_vline_interp(n, vl, ystop - yoff + 1, ur->channels, lr->channels) < 0){
+          return -1;
+        }
+      }else{
+        if(ncplane_vline(n, vl, ystop - yoff + 1) < 0){
+          return -1;
+        }
       }
     }
   }