code: private void setSorterCheckBoxes() {
  
          SorterTableColumnModel sorter = MainFrame.getInstance().getSorter();
  
          for (SortableCheckBox c : checkBoxSortList) {
              c.setSelected(sorter.isShown(c.sortable));
          }
      }
docs: Sets the checkboxes in the sorter panel to what is shown in the
  MainFrame. This assumes that sorterTableColumnModel will return the list
  of which box is checked in the same order as the order that sorter panel
  has.