private void onSphereClick(Object sender, EventArgs e)
 {
     Selection = NormalSelection.Sphere;
     changeMessage(sender, e);
 }
 private void onMeanClick(Object sender, EventArgs e)
 {
     Selection = NormalSelection.Mean;
     changeMessage(sender, e);
 }
 private void onAreaClick(Object sender, EventArgs e)
 {
     Selection = NormalSelection.Area;
     changeMessage(sender, e);
 }
 private void onGaussClick(Object sender, EventArgs e)
 {
     Selection = NormalSelection.Gauss;
     changeMessage(sender, e);
 }
 private void onEquallyClick(Object sender, EventArgs e)
 {
     Selection = NormalSelection.Equal;
     changeMessage(sender, e);
 }