private void RefreshInstruments(IInstrument selectedInstrument = null, ITuning selectedTuning = null) { Instruments = AppVM.GetInstruments(); SelectedInstrument = null; if (null != selectedInstrument && null != Instruments) { foreach (ObservableInstrument oi in Instruments) { if (oi.Instrument == selectedInstrument) { SelectedInstrument = oi; break; } } } if (null != SelectedInstrument) { Tunings = SelectedInstrument.GetTunings(); SelectedTuning = null; if (null != selectedTuning && null != Tunings) { foreach (ObservableTuning ot in Tunings) { if (ot.Tuning == selectedTuning) { SelectedTuning = ot; break; } } } } }