Here is my code, where I have Column with checkboxes and header is checkbox too. When header checkbox is selected all cell's checkboxes are selected too. If in one of the cell the checkbox is unchecked, uncheck the header too.

// html markup 

<igtbl:TemplatedColumn basecolumnname="Read" key="Read" type="CheckBox" datatype="System.Boolean" allowupdate="Yes" width="20px">
       <HeaderTemplate>
           <input id="chboxNotificationsHeaderCheck" onclick="checkHeader_OnClick_Read('<%= GridNotificationSortByRead.ClientID %>',this)" type="checkbox">
       </HeaderTemplate>
       <HeaderStyle customrules="padding: 0px; text-align: right;"></HeaderStyle>
</igtbl:TemplatedColumn>

..........

<ClientSideEvents AfterCellUpdateHandler="grid_OnAfterCellUpdate_Read" />

// javascript code 

// Function for grids where the check column name is "Read"
function grid_OnInitializeLayout_Read(gridName)
{      
    // Check all Rows checkboxes if they are checked
    var checkboxColumnName = "Read";
    var oGrid = igtbl_getGridById(gridName);
    for(var i = 0; i &lt; oGrid.Rows.length; i++)
    {
        var oRow = oGrid.Rows.getRow(i);
        var cell = oRow.getCellFromKey(checkboxColumnName);
        var cellCheckValue = oRow.getCellFromKey(checkboxColumnName).getValue();
        // if at least one is unchecked, set the variable and return from the function
        if (!cellCheckValue)
        {
            document.getElementById(cell.Column.Id).children[0].checked = false;
            return;
        }     
    }
   
    // Change Header checkbox
    document.getElementById(cell.Column.Id).children[0].checked = true;
}

// Function for grids where the check column name is "Read"
function checkHeader_OnClick_Read(gridName, cellId)
{
    var checkboxColumnName = "Read";
    var oGrid = igtbl_getGridById(gridName);
    var oRows = oGrid.Rows;   
    var cellEvent = oGrid.Events.AfterCellUpdate[0];
    oGrid.Events.AfterCellUpdate[0] = "";
    for(var i = 0; i &lt; oRows.length; i++)
    {
        var oRow = oRows.getRow(i);

        // this calls AfterCellUpdate, that is why we use IsInHeaderClickHandler
        oRow.getCellFromKey(checkboxColumnName).setValue(sender.checked);
       
        // This works only for the multi bind grids, for other cases the count is 0
        for(var j = 0;j &lt; oRow.ChildRowsCount; j++)
        {
            chRowId = oRow.Id + "_" + j.toString();
            oChRow = igtbl_getRowById(chRowId);
            oChRow.getCellFromKey("IsSelectedChild").setValue(oRow.getCellFromKey(checkboxColumnName).getValue());
        }
    }
    oGrid.Events.AfterCellUpdate[0] = cellEvent;
}

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And everything was fine, before I put the last version of the Infragistics controls. Now in some button event handler (when my button is clicked), the new state of the checkboxes isn't right. All rows are with Unchanged data. 

I don't know how to fix this problem. Pls, help

Iva 

 I tried getting the code examples above to work but did not have any success.  What is calling

function igrdInitializeLayout(object)?   Do I need to make a call to this function somewhere?

Thanks 

ok I found it hope this helps someone else save some time, this worked for me

        var object = eval(oGrid.Rows.getRow(i).getCell(0).getValue(checked)); 

           oGrid.Rows.getRow(i).getCell(0).setValue(true);

      else

Ok I got it to work! half way though!! how can I check the value and select / and unselect all?? right now it selects everything but I cant seem to figure a way out to revesr it I tried doing this

//oGrid.Rows.getRow(i).getCell(0).setValue(checked);

else