title: How to implement Expand/Collapse for a table with Multiple columns - GWT - Google Visualization API
body: <p>I have list of Items with parent child relation.
  At present I am displaying them in a single table. In each row, fist column starts with number of '-'s indicating the depth.</p>
  
  <p>Now I want show only top level items first and with a '+' button before that.
  When the user clicks on the '+' button it should turn to '-' and the children of that particular Item need to be displayed.</p>
  
  <p>So, Please help me how to implement that Expand and Collapse functionality in GWT. </p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I have my Items in a tree format.
  Now I am creating a DataTable and Displaying it using GoogleTableChart
  The code as follows:</p>
  
  <pre><code>            DataTable data = DataTable.create();
              data.addColumn(ColumnType.STRING, "Item Name ");
              data.addColumn(ColumnType.STRING, "Item Id");
              data.addColumn(ColumnType.NUMBER, "Quantity");
              data.addColumn(ColumnType.NUMBER, "Price ($)");
              data.addRows(treeList.size());
              int i=0;
              while(i&lt;treeList.preOrderTraversal().size())
              {
                  int col=0;
                  Item d=(Item) treeList.preOrderTraversal().get(i);
                  int level=d.getLevel();
                  //setting values to DataTable goes here
                  i++;
              } 
              GoogleTableChart tblChart = new GoogleTableChart();
              vPanel.add(tblChart.showFlexibleTable1(data));
  </code></pre>