Author: Tomas Rutkauskas

Say I have a TOutline with these nodes:

Parent1
Node1
Node2
Node3
Parent2
Parent3

And I need to change the order of the nodes. How can I for example step Node2 down 
one step at a time and disable any movement when there are no more nodes to move 
past at that level (just after Node3). I need to restrict the stepping inside a 
group/ level and that it don't move to another parent.

Answer:

Look in the help file for the TTreeNode methods GetNextSibling, GetPrevSibling and 
MoveTo. Say you have a form with a tree view and two buttons, labelled up and down. 
The code for the onclick events of the up button would look something like this:

1   procedure UpOnClick
2   var
3     PrevSibling: TTreeNode;
4   begin
5     {If no node is selected, exit the procedure}
6     if MyTreeView.Selected = nil then
7       Exit;
8     {If the node the user is trying to move is not a child node, exit the procedure}
9     if MyTreeView.Selected.Level <> 1 then
10      Exit;
11    with MyTreeView.Selected do
12    begin
13      PrevSibling := GetPrevSibling;
14      if PrevSibling <> nil then
15        MoveTo(PrevSibling, naInsert);
16    end;
17  end;
18  
19  procedure DownOnClick
20  var
21    NextSibling: TTreeNode;
22  begin
23    {If no node is selected, exit the procedure}
24    if MyTreeView.Selected = nil then
25      Exit;
26    {If the node the user is trying to move is not a child node, exit the procedure}
27    if MyTreeView.Selected.Level <> 1 then
28      Exit;
29    with MyTreeView.Selected do
30    begin
31      NextSibling := GetNextSibling;
32      if NextSibling <> nil then
33        NextSibling.MoveTo(MyTreeView.Selected, naInsert);
34    end;
35  end;