By default, the ExpandColumns property is empty. Use the ExpandColumns property to display the columns on multiple levels, or to allow your users to expand/collapse the columns. The DisplayExpandButton property specifies whether the column's header displays a +/- ( expanding button ), to let user expands or collapse the column, when it is clicked. The Expanded property expands programmatically a column. The control fires the LayoutChanged event when the user expands or collapse a column. Use the ExpandItem property to expand or collapse an item. The Index property indicates the column's index. The Visible property specifies whether a column is Visible or hidden.

The control performs showing/hiding the child columns as follow:

• If the column is expanded, the child columns are shown, and the current column is hidden, if the index of itself it is not included in the ExpandColumns property.
• If the column is collapsed, the recursively child columns are hidden, and the current column is shown.

The following screen shot shows the control's expandable header:

The following movie shows how you can use the Expandable Header support.