private void typeCombo_SelectedIndexChanged(object sender, EventArgs e) { var combo = sender as ComboBox; if (combo == null) { return; } if (combo.SelectedIndex == (int)EntryType.Movie && (this as AddMovieForm) == null) { var form = new AddMovieForm(m_context); form.Location = Location; form.StartPosition = FormStartPosition.Manual; form.Show(); AddFormManager.SwitchForm(form); } if (combo.SelectedIndex == (int)EntryType.Book && (this as AddBookForm) == null) { var form = new AddBookForm(m_context); form.Location = Location; form.StartPosition = FormStartPosition.Manual; form.Show(); AddFormManager.SwitchForm(form); } }