' Return the number of checked nodes in the specified tree
Public Function CountCheckedNodes(ByVal rootNode As TreeNode) As Integer
Dim count As Integer = 0
' count the root node, if checked
If rootNode.Checked Then count = 1
' check the child nodes, by recursively calling this function for all of
' them
Dim tvn As TreeNode
For Each tvn In rootNode.Nodes
count += CountCheckedNodes(tvn)
Next
Return count
End Function