/// <summary>
 /// Event handler for the <see cref="PickingTool.InputValidationRequested"/> event.
 /// </summary>
 /// <param name="sender">The sender.</param>
 /// <param name="eventArgs">The <see cref="InputValidationEventArgs"/> instance containing the event data.</param>
 private void OnInputValidationRequested(object sender, InputValidationEventArgs eventArgs)
 {
     if (this.pickedPoints.Count < Math.Max(this.inputRange.Minimum, 2))
     {
         eventArgs.ContinueSession = true;
     }
 }
        /// <summary>
        /// Event handler for the <see cref="PickingTool.InputValidationRequested"/> event.
        /// </summary>
        /// <param name="sender">The sender object.</param>
        /// <param name="eventArgs">The event argument for the handler.</param>
        private void OnInputValidationRequested(object sender, InputValidationEventArgs eventArgs)
        {
            // This is for simply illustrative purposes. The proper way
            // to get this same functionality is to set the input range to
            // be exactly 2. The API takes care to keep the session going
            // until the minimun amount has been picked.

            // NOTE: When the session has been interrupted by the user, setting
            // the ContinueSession to true has no effect.
            if (this.pickedPoints.Count < Math.Max(this.inputRange.Minimum, 2))
            {
                eventArgs.ContinueSession = true;
            }
        }