Hello Kanwar,

The shared XamComboEditor does not have a SelectAll checkbox feature. To work around this I recommend creating a user control and add a wpf Checkbox somewhere above the combo and handle it's Checked/Unchecked events to add logic which toggles the IsSelected items for each item otherwise it clears the items from the SelctedItems collection.

eg.

private void Select_Deselect()
        {
            foreach (var item in combo.Items)
            {
                item.IsSelected = true;
            }
        }
 
        private void CheckBox_Checked(object sender, RoutedEventArgs e)
        {
            Select_Deselect();
        }
 
        private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
        {
            multiChbCombo.SelectedItems.Clear();
        }

Otherwise you'll have to modify the default style for the XamComboEditor. This was explained here:

http://es.infragistics.com/community/forums/p/64661/327814.aspx#327814

Please submit a new product idea to have this features added at ideas.infragistics.com

Let me know if you have any questions.