title: How can be combo box value change process interrupted?
body: <p>I am writing on c# with visual interface. Part of the logic consists of a set of values changing depended on which one of them (sets) is selected in the combo box.</p>
  
  <p>Changes in the value sets can be saved or not. There is a need to offer an opportunity for user to save unsaved changes or reject them when he chooses a different item (set) in the combo box. It is imperative that when the message box with yes/no is presented combo box still displayed the old value, and only after that, depending on user's choice displayed new or old.</p>
  
  <p>The sequence should be:</p>
  
  <p>user uses keys or drop-down to select new item -> event is fired and form stops all of its processing -> my code cancels the change or lets it go through -> (if not cancelled) combo box is redrawn with new value.</p>
  
  <p>N.B. Following events were tried and proved not to be adequate:</p>
  
  <ul>
  <li>SelectedIndexChanged</li>
  <li>SelectedValueChanged</li>
  <li>SelectionChangeCommitted</li>
  <li>Validating</li>
  <li>DropDownClosed</li>
  </ul>