Public Sub New()
   MyBase.New()

   'This call is required by the Windows Form Designer.
   InitializeComponent()

   richTextBox1.AllowDrop = True

End Sub

Private Sub listBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles listBox1.MouseDown
   ' Determines which item was selected.
   Dim lb As ListBox = CType(sender, ListBox)
   Dim pt As New Point(e.X, e.Y)
   'Retrieve the item at the specified location within the ListBox.
   Dim index As Integer = lb.IndexFromPoint(pt)

   ' Starts a drag-and-drop operation.
   If index >= 0 Then
      ' Retrieve the selected item text to drag into the RichTextBox.
      lb.DoDragDrop(lb.Items(index).ToString(), DragDropEffects.Copy)
   End If
End Sub 'listBox1_MouseDown


Private Sub richTextBox1_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragEnter
   ' If the data is text, copy the data to the RichTextBox control.
   If e.Data.GetDataPresent("Text") Then
      e.Effect = DragDropEffects.Copy
   End If
End Sub 'richTextBox1_DragEnter

Private Sub richTextBox1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragDrop
   ' Paste the text into the RichTextBox where at selection location.
   richTextBox1.SelectedText = e.Data.GetData("System.String", True).ToString()
End Sub 'richTextBox1_DragDrop

   public Form1()
   {
      InitializeComponent();
      // Sets the control to allow drops, and then adds the necessary event handlers.
      this.richTextBox1.AllowDrop = true;
   }
    
   private void listBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
   {
      // Determines which item was selected.
      ListBox lb =( (ListBox)sender);
      Point pt = new Point(e.X,e.Y);
      //Retrieve the item at the specified location within the ListBox.
      int index = lb.IndexFromPoint(pt);

      // Starts a drag-and-drop operation.
      if(index>=0) 
      {
         // Retrieve the selected item text to drag into the RichTextBox.
         lb.DoDragDrop(lb.Items[index].ToString(), DragDropEffects.Copy);
      }
   }

   private void richTextBox1_DragEnter(object sender, DragEventArgs e)
   {
      // If the data is text, copy the data to the RichTextBox control.
      if(e.Data.GetDataPresent("Text"))
         e.Effect = DragDropEffects.Copy;
   }

   private void richTextBox1_DragDrop(object sender, DragEventArgs e) 
   {
      // Paste the text into the RichTextBox where at selection location.
      richTextBox1.SelectedText =  e.Data.GetData("System.String", true).ToString();
   }

public:
   Form1()
   {
      InitializeComponent();

      // Sets the control to allow drops, and then adds the necessary event handlers.
      this->richTextBox1->AllowDrop = true;
   }

private:
   void listBox1_MouseDown( Object^ sender, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determines which item was selected.
      ListBox^ lb = (dynamic_cast<ListBox^>(sender));
      Point pt = Point(e->X,e->Y);

      //Retrieve the item at the specified location within the ListBox.
      int index = lb->IndexFromPoint( pt );

      // Starts a drag-and-drop operation.
      if ( index >= 0 )
      {
         // Retrieve the selected item text to drag into the RichTextBox.
         lb->DoDragDrop( lb->Items[ index ]->ToString(), DragDropEffects::Copy );
      }
   }

   void richTextBox1_DragEnter( Object^ /*sender*/, DragEventArgs^ e )
   {
      // If the data is text, copy the data to the RichTextBox control.
      if ( e->Data->GetDataPresent( "Text" ) )
            e->Effect = DragDropEffects::Copy;
   }

   void richTextBox1_DragDrop( Object^ /*sender*/, DragEventArgs^ e )
   {
      // Paste the text into the RichTextBox where at selection location.
      richTextBox1->SelectedText = e->Data->GetData( "System.String", true )->ToString();
   }