fixed the issue reported by sander (gaps at left columns button due to round-offs)

tag.c

@@ -106,6 +106,9 @@ dotile(Arg *arg)
 				c->x = sx + mw;
 				c->y = sy + (i - 1) * h + bh;
 				c->w = w - 2;
+				if(i + 1 == n)
+					c->h = sh - c->y - 2;
+				else
 					c->h = h - 2;
 			}
 			else { /* fallback if h < bh */