eventhander.cs

[Transaction(TransactionMode.Manual)]
    public class test : IExternalCommand
    {
        public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
        {
           
            commandData.Application.DialogBoxShowing += new EventHandler<DialogBoxShowingEventArgs>(OnDialogShowing);
            commandData.Application.Application.FailuresProcessing += new EventHandler<FailuresProcessingEventArgs>(OnFailuresProcessing);
            commandData.Application.Application.FailuresProcessing -= OnFailuresProcessing;
            commandData.Application.DialogBoxShowing -= OnDialogShowing;
            return Result.Succeeded;
        }
        private static void OnFailuresProcessing(object sender, Autodesk.Revit.DB.Events.FailuresProcessingEventArgs e)
        {
            FailuresAccessor failuresAccessor = e.GetFailuresAccessor();
            IEnumerable<FailureMessageAccessor> failureMessages = failuresAccessor.GetFailureMessages();
            foreach (FailureMessageAccessor failureMessage in failureMessages)
            {
                if (failureMessage.GetSeverity() == FailureSeverity.Warning)
                {
                    failuresAccessor.DeleteWarning(failureMessage);
                }
            }
            e.SetProcessingResult(FailureProcessingResult.Continue);
        }

        private static void OnDialogShowing(object o, DialogBoxShowingEventArgs e)
        {
            if (e.Cancellable)
            {
                e.Cancel();
            }
            //worry about this later - 1002 = cancel
            if (e.DialogId == "TaskDialog_Unresolved_References")
            {
                e.OverrideResult(1002);
            }
            //Don't sync newly created files. 1003 = close
            if (e.DialogId == "TaskDialog_Local_Changes_Not_Synchronized_With_Central")
            {
                e.OverrideResult(1003);
            }
            if (e.DialogId == "TaskDialog_Save_Changes_To_Local_File")
            {
                //Relinquish unmodified elements and worksets
                e.OverrideResult(1001);
            }
        }

        
    }