private void deleteToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (this.selected is SimVehicle)
            {
                // vehicle
                SimVehicle isv = (SimVehicle)this.selected;

                // notfy
                SimulatorOutput.WriteLine("Removed Vehicle: " + isv.SimVehicleState.VehicleID.ToString());

                // remove
                this.displayObjects.Remove(this.selected);
                this.Simulation.simEngine.Vehicles.Remove(isv.VehicleId);
                this.Simulation.clientHandler.Remove(isv.VehicleId);
                this.Simulation.OnClientsChanged();

                if (this.tracked != null && this.tracked.VehicleId.Equals(isv.VehicleId))
                {
                    this.tracked = null;
                }

                // remove selecation
                this.selected = null;

                // properties
                this.Simulation.simEngine.SetPropertyGridDefault();

                // redraw
                this.Invalidate();
            }
        }
        /// <summary>
        /// Delete obstacle
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void deleteObstacleContextToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            if (this.selected is SimObstacle)
            {
                SimObstacle so = (SimObstacle)this.selected;
                this.displayObjects.Remove(so);
                this.Simulation.simEngine.WorldService.Obstacles.Remove(so.ObstacleId);
                this.Simulation.simEngine.SetPropertyGridDefault();
                this.selected = null;

                SimulatorOutput.WriteLine("Removed Obstacle: " + so.ObstacleId.ToString());

                this.Invalidate();
            }
        }