private void SecondAppBrowseBtn_Click(object sender, RoutedEventArgs e) { var ofd = new Win32.OpenFileDialog() { Filter = "PowerApps Files (*.msapp)|*.msapp" }; var result = ofd.ShowDialog(); if (result == false) { return; } SecondAppPathtxtBox.Text = ofd.FileName; appData2 = mergeProcessor.Extract(ofd.FileName); MainViewModel model = this.DataContext as MainViewModel; model.ScreensFromApp2 = new System.Collections.ObjectModel.ObservableCollection <EntityModel>(appData2.Screens.Select(s => new EntityModel() { Screen = s, Source = "App 2" })); model.ScreensForMergedApp.Clear(); foreach (var item in model.ScreensFromApp1) { model.ScreensForMergedApp.Add(item); } foreach (var item in model.ScreensFromApp2) { model.ScreensForMergedApp.Add(item); } }