More Prism stuff

Example/MainWindowViewModel.cs

@@ -0,0 +1,22 @@
+using System.Threading.Tasks;
+using System.Windows.Input;
+using Prism.Commands;
+using Prism.Mvvm;
+
+namespace Example
+{
+    public class MainWindowViewModel : BindableBase
+    {
+        public MainWindowViewModel()
+        {
+            UpdateCommand = new DelegateCommand<string>(async x => await UpdateAsync(x).ConfigureAwait(false));
+        }
+
+        private Task UpdateAsync(string startup) =>
+            bool.TryParse(startup, out var isStartup)
+                ? Katteker.UserInterface.CheckForUpdateAsync(isStartup)
+                : Task.FromResult(true);
+
+        public ICommand UpdateCommand { get; }
+    }
+}