property Items.CellHasButton([Item as Variant], [ColIndex as Variant]) as Boolean

Retrieves or sets a value indicating whether the cell has associated a push button or not.

TypeDescription
Item as Variant A long expression that indicates the item's handle.
ColIndex as Variant A long expression that indicates the column's index, a string expression that indicates the column's caption or the column's key.
Boolean A boolean expression that indicates whether the cell contains a button.

When cell's button is clicked the control fires CellButtonClick event. The caption of the push button is specified by the CellCaption property. 

The following sample sets the cells of the first column to be of button type, and displays a message if the button is clicked:

Private Sub ExplorerTree1_AddItem(ByVal Group As EXPLORERTREELibCtl.IGroup, ByVal Item As EXPLORERTREELibCtl.HITEM)
    With Group.Items
        .CellHasButton(Item, 0) = True
    End With
End Sub

Private Sub ExplorerTree1_CellButtonClick(ByVal Group As EXPLORERTREELibCtl.IGroup, ByVal Item As EXPLORERTREELibCtl.HITEM, ByVal ColIndex As Long)
    MsgBox "The cell '" & Group.Items.CellCaption(Item, ColIndex) & "' has been clicked"
End Sub

Note: A cell is the intersection of an item with a column. All properties that has an Item and a ColIndex parameters are referring to a cell. The Item parameter represents the handle of an item, and the ColIndex parameter indicates an index ( a numerical value, see Column.Index property ) of a column , the column's caption ( a string value, see Column.Caption property ), or a handle to a cell. Here's few hints how to use properties with Item and ColIndex parameters:

Group.Items.CellBold(, Group.Items.ItemCell(Group.Items(0), 0)) = True
Group.Items.CellBold(Group.Items(0), 0) = True
Group.Items.CellBold(Group.Items(0), "ColumnName") = True