//this method zooms the map to the selected location, after the user double-clicks the point locaction in the listbox
        private void lstMissingVertices_DoubleClick(object sender, EventArgs e)
        {
            try
            {
                IPoint    pPointXY = new PointClass();
                double    X;
                double    Y;
                object[]  XY;
                IEnvelope pEnvelope;

                XY = lstMissingVertices.SelectedItem.ToString().Split(' ');
                X  = Convert.ToDouble(XY.GetValue(0));
                Y  = Convert.ToDouble(XY.GetValue(1));

                //set the point's xy values
                pPointXY.X = X;
                pPointXY.Y = Y;

                pEnvelope = pActiveView.Extent;
                pEnvelope.CenterAt(pPointXY);
                pActiveView.Extent = pEnvelope;

                pMap.MapScale = 100;

                pActiveView.Refresh();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error Message: " + Environment.NewLine + ex.Message + Environment.NewLine + Environment.NewLine +
                                "Error Source: " + Environment.NewLine + ex.Source + Environment.NewLine + Environment.NewLine +
                                "Error Location:" + Environment.NewLine + ex.StackTrace,
                                "AGRC Custom Tools ArcMap Error!", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
        }