你可以在TreeView.OnDragOver 事件中如下檢測是否可移入?    procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
Var
  Node : TTreeNode;
begin
  Accept := False;
  If Not (Source Is dbGrid) Then Exit;
  Node := GetNodeAt(X,Y);
  If Node <> nil Then Begin
    // 不是[老師4]或[教師5] 則可以接受
    If Pos(',' Node.Text ',',',老師4,教師5,') =0 Then
      Accept := True;
  End;
end;