RadioMenuFlyoutItem API review

active/RadioMenuFlyoutItem/RadioMenuFlyoutItem.md

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+# Background
+A [MenuFlyoutItem](https://docs.microsoft.com/uwp/api/Windows.UI.Xaml.Controls.MenuFlyoutItem) is an item
+in a menu, be it a context menu ([MenuFlyout](https://docs.microsoft.com/uwp/api/Windows.UI.Xaml.Controls.MenuFlyout))
+or a [MenuBarItem](https://docs.microsoft.com/uwp/api/Windows.UI.Xaml.Controls.MenuBarItem).
+
+The new RadioMenuFlyoutItem in this spec is a MenuFlyoutItem that displays and behaves like a radio button
+(can be checked/unchecked, and in a group only one is selected at a time).
+
+# Description
+A radio menu flyout item is a menu item that is mutually exclusive with other radio menu items in its group. 
+This control contol allows you to present users with menus containing multiple options, where a user would choose only one of these options at a given time.
+
+
+# Examples
+
+## Create RadioMenuFlyoutItems
+*RadioMenuFlyoutItem* can be added into a *MenuBarItem*, *MenuFlyout*, or *MenuFlyoutSubItem*. The following example shows three radio menu flyout items as the content of a cascading menu flyout.
+
+![Three radio menu flyout items in a View goup that allow a user to select the size of icons](RadioMenuFlyoutItem.png)
+
+````Xaml
+<MenuFlyout>
+    <MenuFlyoutSubItem Text="View">
+        <muxc:RadioMenuFlyoutItem Text="Small icons"/>
+        <muxc:RadioMenuFlyoutItem Text="Medium icons" IsChecked="True"/>
+        <muxc:RadioMenuFlyoutItem Text="Large icons"/>
+    </MenuFlyoutSubItem>
+</MenuFlyout>
+````
+
+## Group RadioMenuFlyoutItem into multiple sets
+Radio menu flyout items work in groups, and users can only select one item in a radio menu flyout item group. To create multiple groups of radio buttons within a single menu, be sure to specify the `GroupName` property of each set.
+
+![Two groups of radio menu flyout items within a View menu bar item](RadioMenuFlyoutItem2.png)
+
+````Xaml
+<muxc:MenuBar>
+    <muxc:MenuBarItem Title="View">
+        <MenuFlyoutItem Text="Open"/>
+        <MenuFlyoutSeparator/>
+        <muxc:RadioMenuFlyoutItem Text="Landscape" GroupName="OrientationGroup"/>
+        <muxc:RadioMenuFlyoutItem Text="Portrait" GroupName="OrientationGroup" IsChecked="True"/>
+        <MenuFlyoutSeparator/>
+        <muxc:RadioMenuFlyoutItem Text="Small icons" GroupName="SizeGroup"/>
+        <muxc:RadioMenuFlyoutItem Text="Medium icons" IsChecked="True" GroupName="SizeGroup"/>
+        <muxc:RadioMenuFlyoutItem Text="Large icons" GroupName="SizeGroup"/>
+    </muxc:MenuBarItem>
+</muxc:MenuBar>
+````
+
+# API Details
+````c#
+[webhosthidden]
+unsealed runtimeclass RadioMenuFlyoutItem : Windows.UI.Xaml.Controls.MenuFlyoutItem
+{
+    RadioMenuFlyoutItem();
+
+    /// Gets or sets whether the RadioMenuFlyoutItem is checked
+    Boolean IsChecked;
+
+    /// Gets or sets the name that specifies which RadioMenuFlyoutItem controls are mutually exclusive
+    String GroupName;
+
+    static Windows.UI.Xaml.DependencyProperty IsCheckedProperty{ get; };
+    static Windows.UI.Xaml.DependencyProperty GroupNameProperty{ get; };
+}
+````