Add page for IsBackgroundTransparent (#3672)

* Add page for IsBackgroundTransparent

* updates

* add page for EnterDisplayMode

* updates from review, formatting

Author: jwmsft

hub/apps/api-reference/interface-members/iaccesskeymanagerstaticsdisplaymode-enterdisplaymode.md

@@ -0,0 +1,43 @@
+---
+title: IAccessKeyManagerStaticsDisplayMode.EnterDisplayMode method
+description: Specifies that keytips for currently valid access keys should be displayed and the access keys enabled.
+ms.topic: article
+ms.date: 07/28/2023
+ms.author: jimwalk
+author: jwmsft
+ms.localizationpriority: low
+---
+
+# IAccessKeyManagerStaticsDisplayMode.EnterDisplayMode(XamlRoot) method
+
+## Definition
+
+Namespace: Windows.UI.Xaml.Input
+
+Specifies that keytips for currently valid access keys should be displayed and the access keys enabled.
+
+```csharp
+[uuid(3e602318-59f6-5f2c-9752-bcbb9c907d45)]
+interface IAccessKeyManagerStaticsDisplayMode 
+{
+    void EnterDisplayMode(Windows.UI.Xaml.XamlRoot xamlRoot);
+};
+```
+
+### Parameters
+
+**`xamlRoot`** [XamlRoot](/uwp/api/windows.ui.xaml.xamlroot)
+
+The XamlRoot for the currently focused element. Cannot be `null`.
+
+## Windows requirements
+
+<table><tr><td>Device family</td><td>Windows 11, version 22H2 (introduced in 10.0.22621.0)</td></tr></table>
+
+## Remarks
+
+Calling this method has no effect if the scope is already in display mode. If another scope is in display mode, it will be exited.
+
+After calling this method, the [IsDisplayModeEnabled](/uwp/api/windows.ui.xaml.input.accesskeymanager.isdisplaymodeenabled) property will be `true`.
+
+Call [ExitDisplayMode](/uwp/api/windows.ui.xaml.input.accesskeymanager.exitdisplaymode) to disable display mode.

hub/apps/api-reference/interface-members/ixamlsourcetransparency-isbackgroundtransparent.md

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+---
+title: IXamlSourceTransparency.IsBackgroundTransparent property
+description: Gets or sets the background transparency of all DesktopWindowXamlSource objects on the current thread.
+ms.topic: article
+ms.date: 07/28/2023
+ms.author: jimwalk
+author: jwmsft
+ms.localizationpriority: low
+---
+
+# IXamlSourceTransparency.IsBackgroundTransparent property
+
+## Definition
+
+Namespace: Windows.UI.Xaml
+
+Gets or sets a value that specifies whether the background of all DesktopWindowXamlSource objects on the current thread is transparent.
+
+```csharp
+[uuid(06636c29-5a17-458d-8ea2-2422d997a922)]
+interface IXamlSourceTransparency
+{
+    Boolean IsBackgroundTransparent;
+};
+```
+
+### Property Value
+
+[Boolean](/dotnet/api/system.boolean)
+
+`true` if the window background is transparent; otherwise, `false`.
+
+## Windows requirements
+
+<table><tr><td>Device family</td><td>Windows 10 (introduced in 10.0.17763.0)</td></tr></table>
+
+## Examples
+
+This example shows the [DesktopWindowXamlSource](/uwp/api/windows.ui.xaml.hosting.desktopwindowxamlsource) objects being configured to have a transparent background.
+
+```csharp
+// Make all DesktopWindowXamlSource objects on this
+// thread have a transparent background.
+var xamlSourceTransparency = (IXamlSourceTransparency)Window.Current;
+xamlSourceTransparency.IsBackgroundTransparent = true;
+```
+
+With `IsBackgroundTransparent` set to `true`, if the following is set as the content of an island, the first column will show the content of the host but the second column will be white.
+
+```xaml
+<Grid ColumnDefinitions="Auto,*">
+    <TextBlock>Column 0 text</TextBlock>
+
+    <Border Grid.Column="1" Background="White">
+        <TextBlock>Column 1 text</TextBlock>
+    </Border>
+</Grid>
+```
+
+## Remarks
+
+The [DesktopWindowXamlSource](/uwp/api/windows.ui.xaml.hosting.desktopwindowxamlsource) class is used to host Xaml in another app. For example, you can use this to host some Xaml content in a WPF or WinForms app. See [Host WinRT XAML controls in desktop apps (XAML Islands)](/windows/apps/desktop/modernize/xaml-islands) for more info.
+
+By default, the XAML content has an opaque background, meaning that it's not possible to have any of the host content behind the XAML show through. (In WinUI3, this behavior is changed; the XAML always has a transparent background.)
+
+Set this property to `true` to give all [DesktopWindowXamlSource](/uwp/api/windows.ui.xaml.hosting.desktopwindowxamlsource) objects on the current thread a transparent background.
+
+This interface is retrieved from a XAML [Window](/uwp/api/windows.ui.xaml.window).
+
+> [!NOTE]
+> Setting this property to `true` in a XAML UWP app will cause a XAML [Window](/uwp/api/Windows.UI.Xaml.Window) to be transparent as well when it's in full screen mode (when you've called [ApplicationView.TryEnterFullScreenMode](/uwp/api/Windows.UI.ViewManagement.ApplicationView.TryEnterFullScreenMode)).