private void enterButton_Click(object sender, EventArgs e)
        {
            EnterCinema entWind = new EnterCinema(false);

            entWind.ShowDialog();
            if (Cinema.CurUser == null)
            {
                enterButton.Visible    = true;
                registerButton.Visible = true;
                profileButton.Visible  = false;
                exitButton.Visible     = false;
            }
            else
            {
                enterButton.Visible    = false;
                registerButton.Visible = false;
                profileButton.Visible  = true;
                exitButton.Visible     = true;
            }
        }
        private void registerButton_Click(object sender, EventArgs e)
        {
            EnterCinema entWind = new EnterCinema(true);

            entWind.ShowDialog();
        }