how to bind data from a grid to a textbox in an irpt file

Question

i have the following grid

DateCreated |ID   | State  
18/01/2016  |0005 | N

I can get the data in an alert when i double click on the row as following:

    function getData (){
var gridObjects=GridTableData.getGridObject();

var  ID = gridObjects.getCellValueByName(1,"ID");
       alert(ID );
  }



    <tr>
        <td>
        <p align="center"><APPLET NAME="GridTableData" WIDTH="1000" HEIGHT="546" CODE="iGrid" CODEBASE="/XMII/Classes" ARCHIVE="illum8.zip" MAYSCRIPT>
        <PARAM NAME="QueryTemplate" VALUE="SAPInterface/Reporting/SQLQuery_GridTableData">
        <PARAM NAME="DisplayTemplate" VALUE="SAPInterface/Reporting/iGrid_Lights_GridTableData">
      <param name="InitialUpdate" value="false">
       <PARAM NAME="DoubleClickEvent" value="getData">
       </APPLET>
       </td>
       </tr>
 <tr>
 <td width="120" align="left" class="lightgrey"><input type="text" maxlength="10" name="Message_ID" id="" /></td>
</td>
</tr>

how do i now take that ID from the getData function when its doubled clicked and display it in the above textbox?