When you manipulate layers,you only want to handle only for current layer,you can do it by OperateAllLayer property,when you set value as False,it only handle for current layer.or it handle all of layers.
You can do it by code.
Code example:

procedure TMainFrm.Button1Click(Sender: TObject); 
begin 
  MyCAD1.OperateAllLayer:=False; 
end;