I am having difficulty in customizing default tool tip text of PieChart.Here are the details of of API: gwt-visualization 1.1.2, Gwt2.0 and Gxt 2.1.1. [Here is the link what i have](https://stackoverflow.com/questions/8675379/add-custom-text-to-google-visualization-tooltip-using-gwt-api)  followed , but there is no luck. 

**Code:**

*JSNI:*

```
    private native DataTable addTooltipColumn(DataTable data) /*-{
        data.addColumn({type: 'string', role: 'tooltip'});
        return data;
    }-*/;

```

*DataTable:*

```
 private AbstractDataTable createTable() {
          DataTable data = DataTable.create();
          data.addColumn(ColumnType.STRING, "Task");
          data.addColumn(ColumnType.NUMBER, "Hours per Day");

//Assigning the variable

      data = addTooltipColumn(data);

            List<Integer> asList = Arrays.asList(34,12,34,32,67,21,2,45,2,4,28,5,78);
            data.addRows(asList.size());
            int i=0;
            for (Integer integer : asList) {
                data.setValue(i, 0, "Work"+i);
                data.setValue(i, 1, integer);
                data.setValue(i, 2, "....Tool Tip Txt...");
                i++;
            }
            return data;
          }

```

![Default text on mouse over:](https://i.stack.imgur.com/TBzcM.png)