Argument passed to PreviewInvoke event. Assigning Cancelling to True will cancel the invoking of the trigger.
This is an infrastructure class. Behavior attached to a trigger base object can add its behavior as a listener to TriggerBase.PreviewInvoke.
Inheritance: System.EventArgs
 /// <summary>
 /// Invoke all actions associated with this trigger.
 /// 
 /// </summary>
 /// 
 /// <remarks>
 /// Derived classes should call this to fire the trigger.
 /// </remarks>
 protected void InvokeActions(object parameter)
 {
     if (this.PreviewInvoke != null)
     {
         PreviewInvokeEventArgs e = new PreviewInvokeEventArgs();
         this.PreviewInvoke((object)this, e);
         if (e.Cancelling)
         {
             return;
         }
     }
     foreach (TriggerAction triggerAction in this.Actions)
     {
         triggerAction.CallInvoke(parameter);
     }
 }
 /// <summary>
 /// Invoke all actions associated with this trigger.
 ///
 /// </summary>
 ///
 /// <remarks>
 /// Derived classes should call this to fire the trigger.
 /// </remarks>
 protected void InvokeActions(object parameter)
 {
     if (this.PreviewInvoke != null)
     {
         PreviewInvokeEventArgs e = new PreviewInvokeEventArgs();
         this.PreviewInvoke((object)this, e);
         if (e.Cancelling)
         {
             return;
         }
     }
     foreach (TriggerAction triggerAction in this.Actions)
     {
         triggerAction.CallInvoke(parameter);
     }
 }