void model_SelectionChanged(object sender, Canguro.Model.Model.SelectionChangedEventArgs e)
{
// Activate the grid that corresponds to the picked item (if any)
if (e.Picked is Joint)
MainFrm.SetActiveGridTab(0);
else if (e.Picked is LineElement)
MainFrm.SetActiveGridTab(1);
MainFrm.UpdateArea(UpdateAreaEvent.SelectionChanged, (Canguro.Model.Model)sender, null);
}