(svn r2366) Use SetRedErrorSquare() instead of home brewed version

misc_gui.c

@@ -496,12 +496,8 @@ static void ErrmsgWndProc(Window *w, WindowEvent *e)
 			DeleteWindow(w);
 		break;
 	case WE_DESTROY: {
-		TileHighlightData *thd = _thd_ptr;
+		SetRedErrorSquare(0);
-		TileIndex tile = thd->redsq;
-		thd->redsq = 0;
 		_switch_mode_errorstr = INVALID_STRING_ID;
-		if (tile != 0)
-			MarkTileDirtyByTile(tile);
 		break;
 		}