diff --git a/LehrerApp.Desktop/App.axaml b/LehrerApp.Desktop/App.axaml
index f539bc8..105b99f 100644
--- a/LehrerApp.Desktop/App.axaml
+++ b/LehrerApp.Desktop/App.axaml
@@ -16,6 +16,8 @@
       <StreamGeometry x:Key="IconCalendar">M3,4 H21 V22 H3 Z M5,10 V20 H19 V10 Z M7,2 H9 V7 H7 Z M15,2 H17 V7 H15 Z M7,12 H10 V15 H7 Z M12,12 H15 V15 H12 Z M7,17 H10 V19 H7 Z M12,17 H15 V19 H12 Z</StreamGeometry>
       <StreamGeometry x:Key="IconClock">M12,2 A10,10 0 1 0 12,22 A10,10 0 1 0 12,2 M12,5 A7,7 0 1 1 12,19 A7,7 0 1 1 12,5 M11,7 H13 V12 L17,14 L16,16 L11,13 Z</StreamGeometry>
       <StreamGeometry x:Key="IconClassTeacher">M2,8 L12,3 L22,8 L12,13 Z M6,11 V16 C9,19 15,19 18,16 V11 M22,8 V15</StreamGeometry>
+      <!-- Klassenbuch mit Ausrufezeichen für noch offene Einträge. -->
+      <StreamGeometry x:Key="IconOpenPeriods">M5,2 H19 A2,2 0 0 1 21,4 V20 A2,2 0 0 1 19,22 H5 A2,2 0 0 1 3,20 V4 A2,2 0 0 1 5,2 Z M7,4 V20 H19 V4 Z M11,7 H14 V13 H11 Z M11,15 H14 V18 H11 Z</StreamGeometry>
       <StreamGeometry x:Key="IconSettings">M3,5 H21 V7 H3 Z M8,3 A3,3 0 1 0 8,9 A3,3 0 1 0 8,3 M3,11 H21 V13 H3 Z M16,9 A3,3 0 1 0 16,15 A3,3 0 1 0 16,9 M3,17 H21 V19 H3 Z M10,15 A3,3 0 1 0 10,21 A3,3 0 1 0 10,15</StreamGeometry>
       <StreamGeometry x:Key="IconRefresh">M12,3 A9,9 0 0 1 21,12 H18 A6,6 0 0 0 8,7 L11,10 H3 V2 L6,5 A9,9 0 0 1 12,3 M12,21 A9,9 0 0 1 3,12 H6 A6,6 0 0 0 16,17 L13,14 H21 V22 L18,19 A9,9 0 0 1 12,21</StreamGeometry>
     </ResourceDictionary>
diff --git a/LehrerApp.Desktop/Views/MainWindow.axaml b/LehrerApp.Desktop/Views/MainWindow.axaml
index 7a5f8ee..194f1c0 100644
--- a/LehrerApp.Desktop/Views/MainWindow.axaml
+++ b/LehrerApp.Desktop/Views/MainWindow.axaml
@@ -251,7 +251,14 @@
               </StackPanel>
             </Button>
             <Button Classes="navitem" HorizontalAlignment="Stretch"
-                    Content="Offene Untis-Stunden" Click="OnOpenUntisPeriods"/>
+                    HorizontalContentAlignment="Left" CornerRadius="6"
+                    Click="OnOpenUntisPeriods"
+                    ToolTip.Tip="Offene Untis-Stunden" AutomationProperties.Name="Offene Untis-Stunden">
+              <StackPanel Classes="navcontent" Orientation="Horizontal" Spacing="10">
+                <PathIcon Classes="navicon" Data="{StaticResource IconOpenPeriods}"/>
+                <TextBlock Classes="navlabel" Text="Offene Untis-Stunden"/>
+              </StackPanel>
+            </Button>
             <Button Classes="navitem" Classes.active="{Binding IsSettingsActive}" HorizontalAlignment="Stretch"
                     HorizontalContentAlignment="Left"
                     CornerRadius="6"