How To Close Backstage Tab

ribbon.IsApplicationMenuOpen = false;

<ribbon:RibbonWindow 
    x:Class="TestAPp.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:ribbon="http://schemas.actiprosoftware.com/winfx/xaml/ribbon"
    >
    <Grid x:Name="uxGrid_MainGrid" Margin="6" SnapsToDevicePixels="True">
        <DockPanel SnapsToDevicePixels="True" LastChildFill="True">

            <!-- Ribbon -->
            <ribbon:Ribbon 
                x:Name="uxRibbon"
                DockPanel.Dock="Top"
                TargetContentContainer="{Binding ElementName=uxGrid_MainGrid}"
                IsApplicationButtonVisible="True"
                ApplicationButtonLabel="File"
                IsQuickAccessToolBarCustomizeButtonVisible="False"
                IsMinimizable="True"
                SnapsToDevicePixels="True"
                UseScenicLayout="True"
                IsApplicationMenuOpen="True"
                >
                <ribbon:Ribbon.ApplicationMenu>
                    <ribbon:Backstage x:Name="uxBackstage">
                        <ribbon:Button 
                            Label="Exit" 
                            SnapsToDevicePixels="True"
                            ScreenTipDescription="Exit the application."
                            />
                    </ribbon:Backstage>
                </ribbon:Ribbon.ApplicationMenu>

                <ribbon:Ribbon.Tabs>

                    <ribbon:Tab x:Name="uxRibbonTab_Edit" Label="Edit" Id="Edit" SnapsToDevicePixels="True">
                        <ribbon:Group Label="My Stuff">
                            <ribbon:Button 
                                Label="Do Something"
                                />                           
                        </ribbon:Group>
                    </ribbon:Tab>
                </ribbon:Ribbon.Tabs>
            </ribbon:Ribbon>
        </DockPanel>
    </Grid>
</ribbon:RibbonWindow>