Hi,

Try this:

        private void ultraCombo1_InitializeLayout(object sender, Infragistics.Win.UltraWinGrid.InitializeLayoutEventArgs e)
        {
            e.Layout.Override.HeaderClickAction = Infragistics.Win.UltraWinGrid.HeaderClickAction.SortMulti;
            e.Layout.Override.FixedRowStyle = Infragistics.Win.UltraWinGrid.FixedRowStyle.Top;

            // Assuming that the "--All--" row is the first one.
            e.Layout.Rows[0].Fixed = true;
        }