procedure Tfmain.ImageEnMView1ImageSelect(Sender: TObject; idx: Integer);
var
i: integer;
begin
  // make all layers transparency 100
  for i := 0 to ImageEnView1.LayersCount - 1 do
    ImageEnView1.Layers[i].Transparency := 100;
  // make selected layer the top layer
  ImageEnView1.LayersCurrent := idx;
  // make current layer transparency 255
  with ImageEnView1 do
  begin
    CurrentLayer.Transparency := 255;
    RefreshControls;
  end;
end;