// Compose by LXT
	// this.txtMain.AllowDrop = true;
	
	private void txtMain_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
    {
      if (e.Data.GetDataPresent(DataFormats.FileDrop))
      {
        e.Effect = DragDropEffects.Copy;
      }
    }

    private void txtMain_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
    {
      if (e.Data.GetDataPresent(DataFormats.FileDrop)) // Có thể ko cần
      {
        string[] strFiles = (string[])e.Data.GetData(DataFormats.FileDrop);
        StreamReader reader = new StreamReader(strFiles[0]);
        this.txtMain.Clear();
        this.txtMain.Text = reader.ReadToEnd();
        reader.Close();
      }
    }