void MyMap_ExtentChanging(object sender, ESRI.ArcGIS.Client.ExtentEventArgs e)
{
Envelope ext = e.NewExtent;
XMinText.Text = String.Format("MinX: {0}", Math.Round(ext.XMin, 3));
YMinText.Text = String.Format("MinY: {0}", Math.Round(ext.YMin, 3));
XMaxText.Text = String.Format("MaxX: {0}", Math.Round(ext.XMax, 3));
YMaxText.Text = String.Format("MaxY: {0}", Math.Round(ext.YMax, 3));
}