private void Add_super_Click(object sender, EventArgs e) { string add = Add_sup.Text; if (add == "") { MessageBox.Show("You didn't enter a last name! Please, enter a last name.", "", MessageBoxButtons.OK, MessageBoxIcon.Information); } SomerenUI.AddSuper(add); panel1.Controls.Clear(); Add_sup.Clear(); groupBox1.Text = "Supervisors"; panel1.Controls.Add(Remove_super); panel1.Controls.Add(Remove_sup); panel1.Controls.Add(Remove_s); panel1.Controls.Add(Add_super); panel1.Controls.Add(Add_sup); panel1.Controls.Add(Add_s); panel1.Controls.Add(SomerenUI.showListSupervisors()); }