static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
PosForm posf = new PosForm();
PosSystem poss = new PosSystem(posf);
posf.setPosSystem(poss);
Application.Run(posf);
}
public void setPosSystem(PosSystem poss)
{
this.poss = poss;
cmbofuel.SelectedIndex = 0;
}