Author: Tomas Rutkauskas

I have TreeView1, Button1 and ListBox1. ListBox one has x number of items. I need 
to be able to click Button1 and the items in ListBox1 are inserted as sub-items to 
the selected tree-node.

Answer:

1   var
2     ix: integer;
3     parentnode: TTreeNode;
4   
5     TreeView.Items.BeginUpdate;
6   try
7     parentnode := TreeView.FocusedNode;
8     for ix := 0 to ListBox1.Items.Count - 1 do
9     begin
10      if parentnode = nil then
11        Tree.Items.Add(nil, ListBox1[ix])
12      else
13        Tree.Items.AddChild(parentnode, ListBox1[ix]);
14    end;
15  finally
16    TreeView.Items.EndUpdate;
17  end;