HideShowSingleWindow

<Grid>
     <tb:TaskbarIcon
      IconSource="/Icons/main.ico"
      ToolTipText="SCADA Control Center"
            DoubleClickCommand="{Binding Path=HideShow}">
            <tb:TaskbarIcon.ContextMenu>
                <ContextMenu>
                    <ContextMenu.ItemsSource>
                        <CompositeCollection>
                            <MenuItem Header="Windows" ItemsSource="{Binding Path=RegisteredWindows}">
                                <MenuItem.ItemContainerStyle>
                                    <Style TargetType="{x:Type MenuItem}">
                                        <Setter Property="Header" Value="{Binding Path=Title}" />
                                        <Setter Property="IsCheckable" Value="True" />
                                        <Setter Property="IsChecked" Value="{Binding Path=IsLoaded, Mode=OneWay}"/>
                                        <Setter Property="Command" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=HideShowSingleWindow}" />
                                        <Setter Property="CommandParameter" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=PlacementTarget.SelectedItem}" />
                                    </Style>
                                </MenuItem.ItemContainerStyle>
                            </MenuItem>
                            <MenuItem Header="Show/Hide All" Command="{Binding Path=HideShow}" />
                            <Separator />
                            <MenuItem Header="Exit" Command="{Binding Path=Quit}" />
                        </CompositeCollection>
                    </ContextMenu.ItemsSource>
                </ContextMenu>
            </tb:TaskbarIcon.ContextMenu>
     </tb:TaskbarIcon>
</Grid>

<Setter Property="Command" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=HideShowSingleWindow}" />

<Setter Property="Command"
        Value="{Binding RelativeSource={RelativeSource FindAncestor,
                         AncestorType={x:Type ContextMenu}},
                       Path=PlacementTarget.DataContext.HideShowSingleWindow}"/>

<Setter Property="Command" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type tb:TaskbarIcon}}, Path=DataContext.HideShowSingleWindow}" />