/// <summary>
 /// Default constructor.
 /// </summary>
 /// <remarks>Use the <see cref="System.Windows.Forms.NativeWindow.AssignHandle"/>
 /// method to attach this class to the form you want to show popups from.</remarks>
 public DropDownWindowHelper()
 {
     _filter = new DropDownMessageFilter(this);
     _filter.DropDownCancel += new DropDownCancelEventHandler(Popup_Cancel);
 }
 /// <summary>
 /// Default constructor.
 /// </summary>
 /// <remarks>Use the <see cref="System.Windows.Forms.NativeWindow.AssignHandle"/>
 /// method to attach this class to the form you want to show popups from.</remarks>
 public DropDownWindowHelper()
 {
     _filter = new DropDownMessageFilter(this);
     _filter.DropDownCancel += new DropDownCancelEventHandler(Popup_Cancel);
 }