code: protected int getNumOfCols() {
          if (!columns.isEmpty()) return getHeadRegularColCnt() + columns.size();
          if (loaded && !colTitleWidgets.isEmpty()) return getHeadRegularColCnt() + colTitleWidgets.size();
          return getHeadRegularColCnt();
      }
docs: important for body, because exact number of columns should be known when populating