Hello Amit,

I don't believe the UltraDesktopAlert has this functionality built in, but it shouldn't be too difficult to implement an alert "queue" to achieve this desired behavior.

        List<string> alertQueue = new List<string>();
        string alertKey = "ALERTKEY";

        private void ShowAlert(string alertString)
        {
            // if the UltraDesktopAlert is open, queue the new alert
            if (this.ultraDesktopAlert1.IsOpen(this.alertKey))
            {
                this.alertQueue.Add(alertString);
                return;
            }

            // show the new alert
            UltraDesktopAlertShowWindowInfo windowInfo = new UltraDesktopAlertShowWindowInfo(alertString, alertString);
            windowInfo.Key = this.alertKey;
            this.ultraDesktopAlert1.Show(windowInfo);
        }
        private void ultraDesktopAlert1_DesktopAlertClosed(object sender, DesktopAlertClosedEventArgs e)
        {
            // if any alerts are queued, take the first one off the queue and display it.
            if (this.alertQueue.Count > 0)
            {
                string alertString = this.alertQueue[0];
                this.alertQueue.RemoveAt(0);
                this.BeginInvoke((Action)delegate()
                {
                    this.ShowAlert(alertString);
                });
            }
        }

You would call the ShowAlert() method in your code whenever a new alert should be displayed. The DesktopAlertClosed event handler will handle popping any queued alerts off of the queue and display them. I've attached the project if you want to see the whole sample.

Let me know if you need any further details.

Thanks,

Chris