code: public void setWidget (int row, int column, Widget widget, int colSpan, String... styles)
      {
          setWidget(row, column, widget);
          if (colSpan > 0) {
              getFlexCellFormatter().setColSpan(row, column, colSpan);
          }
          setStyleNames(row, column, styles);
      }
docs: Sets the widget in the specified cell, with the specified style and column span.