apps/examples/fb:  Fix calculation of a mask value.
@@ -177,10 +177,12 @@ static void draw_rect1(FAR struct fb_state_s *state,
int y;
row = (FAR uint8_t *)state->fbmem + state->pinfo.stride * rect->pt1.y;
+
startx = (rect->pt1.x >> 3);
endx = (rect->pt2.x >> 3);
- lmask = 0xff << (8 - (rect->pt1.x & 3));
- rmask = 0xff >> (rect->pt2.x & 3);
+
+ lmask = 0xff << (8 - (rect->pt1.x & 7));
+ rmask = 0xff >> (rect->pt2.x & 7);
for (y = rect->pt1.y; y <= rect->pt2.y; y++)
{
