private void tabControl1_SelectedIndexChanged(object sender, EventArgs e) { if (tabControl1.SelectedIndex == 0) { Loops newFrm = new Loops { MdiParent = this, // This set the form parent as the tabClicked Parent = tabControl1.TabPages[0] }; newFrm.Show(); } else if (tabControl1.SelectedIndex == 1) { Enumerables newFrm = new Enumerables { MdiParent = this, // This set the form parent as the tabClicked Parent = tabControl1.TabPages[1] }; newFrm.Show(); } }