private void cajaToolStripMenuItem1_Click(object sender, EventArgs e)
{
_frmCaja = this.instanciaFrmCaja;
if (_frmCaja.WindowState == FormWindowState.Minimized)
{
_frmCaja.WindowState = FormWindowState.Normal;
}
_frmCaja.Show();
}
void frmCaja_Disposed(object sender, EventArgs e)
{
_frmCaja = null;
}