Drag-and-Drop Operation in Windows Forms and C#

private void listBoxA_MouseDown(object sender, MouseEventArgs e)

{

    listBoxA.DoDragDrop(listBoxA.SelectedItem, DragDropEffects.Copy)

}

Step 2:  Perform Drop Operation

1. Set the AllowDrop property of ListBoxB  to true.
   
   
2. In the DragEnter event for the ListBoxB  where the drop will occur, ensure that the data being dragged is of an acceptable type (in this case of Listbox- Text). The code then sets the effect that will happen when the drop occurs to a value in the DragDroeffects enumeration that has these option:
   
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   private void listBoxB_DragEnter(object sender, DragEventArgs e)
   {
       if (e.Data.GetDataPresent(DataFormats.Text))
           e.Effect = DragDropEffects.Copy;
       else
           e.Effect = DragDropEffects.None;
   } 
   
   
3. In the DragDrop event for the control where the drop will occur, use the GetData method to retrieve the data being dragged.
   
   private void listBoxB_DragDrop(object sender, DragEventArgs e)
   {
       listBox2.Items.Add(e.Data.GetData(DataFormats.Text).ToString());
   }