public void RemoveCodeScheme() { if (SelectedCodeScheme == null) { return; } using (UndoTransaction tx = new UndoTransaction(UndoManager)) { StudyUnit.RemoveCodeSchemeFromResponse(SelectedCodeScheme); SelectedCodeScheme.Codes.Clear(); codeSchemes.Remove(SelectedCodeScheme); tx.Commit(); } SelectedCodeScheme = null; }