Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

unit Unit1;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Controls, Forms,
   Dialogs, StdCtrls, ComCtrls;

 type
   TForm1 = class(TForm)
     TreeView1: TTreeView;
     Label1: TLabel;
     procedure TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer);
     procedure TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
       State: TDragState; var Accept: Boolean);
   private
     { Private declarations }
     Procedure MoveNode(TargetNode, SourceNode : TTreeNode);
   public
     { Public declarations }
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 // 
// Procedure which will move node and its subnodes 
// 
Procedure TForm1.MoveNode(TargetNode, SourceNode : TTreeNode);
 var
   nodeTmp : TTreeNode;
   i : Integer;
 begin
   with TreeView1 do
   begin
     nodeTmp := Items.AddChild(TargetNode,SourceNode.Text);
     for i := 0 to SourceNode.Count -1 do
     begin
       MoveNode(nodeTmp,SourceNode.Item[i]);
     end;
   end;
 end;


 procedure TForm1.TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer);
 var
   TargetNode, SourceNode : TTreeNode;
 begin
   with TreeView1 do
   begin
     TargetNode := GetNodeAt(X,Y); // Get target node 
    SourceNode := Selected;
     if (TargetNode = nil) then
     begin
       EndDrag(False);
       Exit;
     end;
     MoveNode(TargetNode,SourceNode);
     SourceNode.Free;
   end;
 end;

 procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
   State: TDragState; var Accept: Boolean);
 begin
   if (Sender = TreeView1) then // If TRUE than accept the draged item 
  begin
     Accept := True;
   end;
 end;

 end.