protected override bool TryHandle(ISet <Key> pressedKeys) { bool hasModifier = pressedKeys.Contains(Key.LeftCtrl) || pressedKeys.Contains(Key.RightCtrl); if (hasModifier && pressedKeys.Contains(Key.O)) { OpenFileDialog openFileDialog = new OpenFileDialog() { Filter = "Midi or LilyPond files (*.mid *.ly)|*.mid;*.ly" }; if (openFileDialog.ShowDialog() == true) { _musicLoader.OpenFile(openFileDialog.FileName); } return(true); } return(false); }