protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
base.OnBackKeyPress(e);
if (CategoryListGrid.Visibility == Visibility.Collapsed)
{
ESRI.ArcGIS.Client.IdentityManager.Current.ChallengeMethod = null;
foreach (IdentityManager.Credential crd in ESRI.ArcGIS.Client.IdentityManager.Current.Credentials)
ESRI.ArcGIS.Client.IdentityManager.Current.RemoveCredential(crd);
ShowMainMenu();
e.Cancel = true;
}
}