Hi sh2311g,

Thank you for posting in the community.

In this scenario I suggest that you use an ASP Checkbox control in your column header's template:

                        

 <asp:CheckBox ID="headerCheckbox" runat="server" AutoPostBack="True" 
                            oncheckedchanged="headerCheckbox_CheckedChanged" />

Here is also some sample code for the server-side handler:

    public void headerCheckbox_CheckedChanged(object sender, EventArgs e)
    {
        CheckBox header = sender as CheckBox;
        if (header.Checked)
        {
            foreach (UltraGridRow row in UltraWebGrid1.Rows)
            {
                row.Cells.FromKey("CheckboxCol").Value = true;
            }
        }
        else
        {
            foreach (UltraGridRow row in UltraWebGrid1.Rows)
            {
                row.Cells.FromKey("CheckboxCol").Value = false;
            }
        }
    }

With this setup you would need to uncheck the header checkbox any time a row checbox is deselected. You may also find the following guide for checking all checkboxes in a column client-side useful:

http://devcenter.infragistics.com/Support/KnowledgeBaseArticle.aspx?ArticleID=5057

Please note that the UltraWebGrid control is now outdated and as of .NetAdvantage 2011 Volume 2 is no longer included in our product package. I would suggest that you consider switching to the WebDataGrid/WebHieararchicalDataGrid. More information regarding these controls is available at:

http://help.infragistics.com/NetAdvantage/ASPNET/2011.2/CLR4.0/?page=Web_WebDataGrid_WebDataGrid.html

Additional samples demonstrating the features of these grids can be found at:
http://samples.infragistics.com/aspnet/

Feel free to contact me if you have any questions.