feat: try to focus on dialog and make tab navigation cycled.

src/Ursa.Themes.Semi/Controls/Dialog.axaml

@@ -19,6 +19,7 @@
             <ControlTemplate TargetType="u:CustomDialogControl">
                 <Border
                     Name="PART_Border"
+                    Focusable="True"
                     Padding="0"
                     HorizontalAlignment="Center"
                     VerticalAlignment="Center"
@@ -152,6 +153,7 @@
                 <Border
                     Name="PART_Border"
                     Padding="0"
+                    Focusable="True"
                     HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
                     VerticalAlignment="{TemplateBinding VerticalAlignment}"
                     BoxShadow="0 0 8 0 #1A000000"

src/Ursa.Themes.Semi/Controls/UrsaWindow.axaml

@@ -65,7 +65,9 @@
                                 Margin="{Binding $parent[u:UrsaWindow].TitleBarMargin}"
                                 LeftContent="{Binding $parent[u:UrsaWindow].LeftContent}"
                                 RightContent="{Binding $parent[u:UrsaWindow].RightContent}" />
-                            <u:OverlayDialogHost IsModalStatusReporter="True" />
+                            <VisualLayerManager>
+                                <u:OverlayDialogHost IsModalStatusReporter="True" />
+                            </VisualLayerManager>
                         </VisualLayerManager.ChromeOverlayLayer>
                         <Panel>
                             <ContentPresenter