double k = 0;
                    IMap pMap = axMapControl1.Map;
                    IActiveView pActiveview = pMap as IActiveView;
                    IPoint pPoint = pActiveview.ScreenDisplay.DisplayTransformation.ToMapPoint(e.x, e.y);
                    ITopologicalOperator pTopolog = pPoint as ITopologicalOperator;
                    IGeometry pGeo = pPoint as IGeometry;
                    k = Convert.ToDouble(textBox8.Text);
                    pGeo = pTopolog.Buffer(k);
                    IRgbColor pRgb = new RgbColorClass();
                    pRgb.RGB = 255;
                    IColor pColor = pRgb;
                    ISimpleFillSymbol pSimfillsym = new SimpleFillSymbolClass();
......................