Collection was modified; enumeration may not execute error when removing a ListItem from a LIstBox

Question

I have two ListBoxes, lstAvailableColors and lstSelectedColors. Between each listbox are two buttons, Add and Remove. When a color or colors is selected in lstAvailableCol

Answer 1

Example on how to remove the selected Items. Here only the selected indices are taken and removed.

   public void RemoveSelectedItems(ListBox listbox)
   {
       List items = GetSelectedItems(listbox);
       foreach (var listItem in items)
       {
           listbox.Items.Remove(listItem);
       }
   }

  public List GetSelectedItems(ListBox listbox)
  {
     int[] selectedIndices = listbox.GetSelectedIndices();
     return selectedIndices.Select(index => listbox.Items[index]).ToList();
  }