Update IsItemsHost on changes to Visibility rather than IsVisible (#3073)

Author: nicolaihenriksen

MaterialDesignThemes.Wpf/TabAssist.cs

@@ -16,20 +16,20 @@ public static class TabAssist
 
     public static bool GetHasUniformTabWidth(DependencyObject element) => (bool)element.GetValue(HasUniformTabWidthProperty);
 
-    internal static bool GetBindableIsItemsHost(DependencyObject obj)
-        => (bool)obj.GetValue(BindableIsItemsHostProperty);
+    internal static Visibility GetBindableIsItemsHost(DependencyObject obj)
+        => (Visibility)obj.GetValue(BindableIsItemsHostProperty);
 
-    internal static void SetBindableIsItemsHost(DependencyObject obj, bool value)
+    internal static void SetBindableIsItemsHost(DependencyObject obj, Visibility value)
         => obj.SetValue(BindableIsItemsHostProperty, value);
 
     internal static readonly DependencyProperty BindableIsItemsHostProperty =
-        DependencyProperty.RegisterAttached("BindableIsItemsHost", typeof(bool), typeof(TabAssist), new PropertyMetadata(false, OnBindableIsItemsHostChanged));
+        DependencyProperty.RegisterAttached("BindableIsItemsHost", typeof(Visibility), typeof(TabAssist), new PropertyMetadata(Visibility.Collapsed, OnBindableIsItemsHostChanged));
 
     private static void OnBindableIsItemsHostChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
         if (d is Panel panel)
         {
-            panel.IsItemsHost = (bool)e.NewValue;
+            panel.IsItemsHost = (Visibility)e.NewValue == Visibility.Visible;
         }
     }
 }

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TabControl.xaml

@@ -50,14 +50,14 @@
                                HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                Focusable="False"
-                               wpf:TabAssist.BindableIsItemsHost="{Binding IsVisible, RelativeSource={RelativeSource Self}}"
+                               wpf:TabAssist.BindableIsItemsHost="{Binding Visibility, RelativeSource={RelativeSource Self}}"
                                KeyboardNavigation.TabIndex="1"
                                Rows="1" />
                   <VirtualizingStackPanel x:Name="HeaderPanel"
                                           HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                           VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                           Focusable="False"
-                                          wpf:TabAssist.BindableIsItemsHost="{Binding IsVisible, RelativeSource={RelativeSource Self}}"
+                                          wpf:TabAssist.BindableIsItemsHost="{Binding Visibility, RelativeSource={RelativeSource Self}}"
                                           KeyboardNavigation.TabIndex="1"
                                           Orientation="Horizontal" />
                 </StackPanel>