(svn r128) Invalid (void) orders in schedule are highlighted in red (Celestar)

lang/english.txt

@@ -2205,6 +2205,8 @@ STR_SERVICE_NON_STOP_AT_TRAIN_DEPOT		:Service non-stop at {TOWN} Train Depot
 STR_HEADING_FOR_TRAIN_DEPOT				:{LTBLUE}Heading for {TOWN} Train Depot
 STR_HEADING_FOR_TRAIN_DEPOT_VEL			:{LTBLUE}Heading for {TOWN} Train Depot, {VELOCITY}
 
+STR_INVALID_ORDER				:{RED} (Invalid Order)
+
 STR_UNKNOWN_DESTINATION			:unknown destination
 STR_8812_EMPTY							:{LTBLUE}Empty
 STR_8813_FROM							:{LTBLUE}{CARGO} from {STATION}

order_gui.c

@@ -119,7 +119,13 @@ static void DrawOrdersWindow(Window *w)
 			{
 				byte color = (i == WP(w,order_d).sel) ? 0xC : 0x10;
 				SET_DPARAM(0, i+1);
-				DrawString(2, y, str, color);
+				if ((ord & OT_MASK) != OT_DUMMY) {
+					DrawString(2, y, str, color);
+				} else {
+					SET_DPARAM16(1, STR_INVALID_ORDER);
+					SET_DPARAM16(2, ord >> 8);
+					DrawString(2, y, str, color);
+				}
 			}
 			y += 10;
 		}