The program starts the nodes' keys with the letters f for factory, g for group, and p for person. This makes it easier to figure out what kind of node each is later.

Private Sub Form_Load()
Dim i As Integer
Dim factory As Node
Dim group As Node
Dim person As Node

    ' Load pictures into the ImageList.
    For i = 1 To 6
        TreeImages.ListImages.Add , , TreeImage(i).Picture
    Next i
    
    ' Attach the TreeView to the ImageList.
    OrgTree.ImageList = TreeImages
    
    ' Create some nodes.
    Set factory = OrgTree.Nodes.Add(, , "f R & D", "R & D", _
        otFactory, otFactory2)
    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        "Engineering", "Engineering", otGroup, otGroup2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Cameron, Charlie", "Cameron, Charlie", otPerson, _
        otPerson2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Davos, Debbie", "Davos, Debbie", otPerson, _
        otPerson2)
    person.EnsureVisible
    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        "Test", "Test", otGroup, otGroup2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Able, Andy", "Andy, Able", otPerson, otPerson2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Baker, Betty", "Baker, Betty", otPerson, otPerson2)
    person.EnsureVisible
    
    Set factory = OrgTree.Nodes.Add(, , "f Sales & " & _
        "Support", "Sales & Support", otFactory, otFactory2)
    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        "Showroom Sales", "Showroom Sales", otGroup, _
        otGroup2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Gaines, Gina", "Gaines, Gina", otPerson, otPerson2)
    person.EnsureVisible
    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        "Field Service", "Field Service", otGroup, otGroup2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Helms, Harry", "Helms, Harry", otPerson, otPerson2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Ives, Irma", "Ives, Irma", otPerson, otPerson2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Jackson, Josh", "Jackson, Josh", otPerson, _
        otPerson2)
    person.EnsureVisible
    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        "Customer Support", "Customer Support", otGroup, _
        otGroup2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Klug, Karl", "Klug, Karl", otPerson, otPerson2)
    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        "Landau, Linda", "Landau, Linda", otPerson, _
        otPerson2)
    person.EnsureVisible
End Sub

Private Function NodeType(test_node As Node) As ObjectType
    If test_node Is Nothing Then
        NodeType = otNone
    Else
        Select Case Left$(test_node.Key, 1)
            Case "f"
                NodeType = otFactory
            Case "g"
                NodeType = otGroup
            Case "p"
                NodeType = otPerson
        End Select
    End If
End Function

' Add a new factory.
Private Sub mnuAddFactory_Click()
Dim name As String
Dim factory As Node

    name = InputBox("Factory Name", "New Factory", "")
    If name = "" Then Exit Sub
    
    Set factory = OrgTree.Nodes.Add(, , "f " & name, name, _
        otFactory, otFactory2)
    factory.EnsureVisible
End Sub

' Add a new group.
Private Sub mnuAddGroup_Click()
Dim name As String
Dim factory As Node
Dim group As Node

    name = InputBox("Group Name", "New Group", "")
    If name = "" Then Exit Sub
    
    ' Find the factory that should hold the new group.
    Set factory = OrgTree.SelectedItem
    If NodeType(factory) = otPerson Then _
        Set factory = factory.Parent
    If NodeType(factory) = otGroup Then _
        Set factory = factory.Parent

    Set group = OrgTree.Nodes.Add(factory, tvwChild, "g " & _
        name, name, otGroup, otGroup2)
    group.EnsureVisible
End Sub

' Add a new person.
Private Sub mnuAddPerson_Click()
Dim name As String
Dim group As Node
Dim person As Node

    name = InputBox("Person Name", "New Person", "")
    If name = "" Then Exit Sub
    
    ' Find the group that should hold the new person.
    Set group = OrgTree.SelectedItem
    If NodeType(group) = otPerson Then _
        Set group = group.Parent

    Set person = OrgTree.Nodes.Add(group, tvwChild, "p " & _
        name, name, otPerson, otPerson2)
    person.EnsureVisible
End Sub

Private Sub mnuNodes_Click()
Dim selected_node As Node
Dim selected_type As ObjectType

    Set selected_node = OrgTree.SelectedItem
    If selected_node Is Nothing Then
        selected_type = otNone
    Else
        selected_type = NodeType(selected_node)
    End If

    ' You can always add a factory.
    
    ' You can add a group if a factory, person, or
    ' group is selected.
    mnuAddGroup.Enabled = (selected_type <> otNone)
    
    ' You can add a person if a group or person
    ' is selected.
    mnuAddPerson.Enabled = (selected_type = otPerson) _
        Or (selected_type = otGroup)
End Sub

When the user moves the mouse, the OrgTree_MouseMove event handler begins a drag by calling the TreeView control's Drag method.

As the user drags the mouse over the TreeView control, its OrgTree_DragOver event handler fires. This routine finds the node under the mouse. If the target node is appropriate (e.g. the dragging node is a person and the target node is a group), the routine sets the TreeView control's DropHighlight property to point to the target node. This highlights the target. If the drop is inappropriate (e.g. dragging a factory onto a group), the code sets the DropHighlight property to Nothing so no node is highlighted.

SFinally, when the user releases the node, the OrgTree_DragDrop event handler checks whether the TreeView's DropHighlight property is Nothing. If DropHighlight is not nothing, then the drop is appropriate so the code makes the source node a child of the target node.

Private SourceNode As Object
Private SourceType As ObjectType
Private TargetNode As Object

' Save the node pressed so we can drag it later.
Private Sub OrgTree_MouseDown(Button As Integer, Shift As _
    Integer, x As Single, y As Single)
    Set SourceNode = OrgTree.HitTest(x, y)
End Sub

' Start a drag if one is not in progress.
Private Sub OrgTree_MouseMove(Button As Integer, Shift As _
    Integer, x As Single, y As Single)
    If Button = vbLeftButton Then
        ' Start a new drag. Note that we do not get
        ' other MouseMove events while the drag is
        ' in progress.
        
        ' See what node we are dragging.
        SourceType = NodeType(SourceNode)

        ' Select this node. When no node is highlighted,
        ' this node will be displayed as selected. That
        ' shows where it will land if dropped.
        Set OrgTree.SelectedItem = SourceNode

        ' Set the drag icon for this source.
        OrgTree.DragIcon = IconImage(SourceType)
        OrgTree.Drag vbBeginDrag
    End If
End Sub

' The mouse is being dragged over the control.
' Highlight the appropriate node.
Private Sub OrgTree_DragOver(Source As Control, x As _
    Single, y As Single, State As Integer)
Dim target As Node
Dim highlight As Boolean

    ' See what node we're above.
    Set target = OrgTree.HitTest(x, y)
    
    ' If it's the same as last time, do nothing.
    If target Is TargetNode Then Exit Sub
    Set TargetNode = target
    
    highlight = False
    If Not (TargetNode Is Nothing) Then
        ' See what kind of node were above.
        If NodeType(TargetNode) + 1 = SourceType Then _
            highlight = True
    End If
    
    If highlight Then
        Set OrgTree.DropHighlight = TargetNode
    Else
        Set OrgTree.DropHighlight = Nothing
    End If
End Sub

' The user is dropping. See if the drop is valid.
Private Sub OrgTree_DragDrop(Source As Control, x As _
    Single, y As Single)
    If Not (OrgTree.DropHighlight Is Nothing) Then
        ' It's a valid drop. Set source node's
        ' parent to be the target node.
        Set SourceNode.Parent = OrgTree.DropHighlight
        Set OrgTree.DropHighlight = Nothing
    End If

    Set SourceNode = Nothing
    SourceType = otNone
End Sub