Only allow username changes when not in game

YJMPD-UWP/ViewModels/SettingsVM.cs

@@ -20,5 +20,13 @@ namespace YJMPD_UWP.ViewModels
                 Settings.Username = value;
             }
         }
+
+        public bool UsernameEnabled
+        {
+            get
+            {
+                return App.Game.Status == Model.GameHandler.GameStatus.STOPPED;
+            }
+        }
     }
 }

YJMPD-UWP/Views/SettingsView.xaml

@@ -11,7 +11,7 @@
         <StackPanel Style="{StaticResource BaseStackPanel}" >
             <StackPanel>
                 <TextBlock Text="Username" Style="{StaticResource Header}" />
-                <TextBox Text="{Binding Username, Mode=TwoWay}" />
+                <TextBox Text="{Binding Username, Mode=TwoWay}" IsEnabled="{Binding UsernameEnabled}"/>
             </StackPanel>
         </StackPanel>
     </ScrollViewer>