<ListView Name="VersionView" 
      Tag = "{Binding DataContext, ElementName = WindowMain}"
      ItemsSource="{Binding Path=VersionList, Mode=OneWay}"
      DataContext="{Binding SelectedItem, ElementName=GroupView, Mode=OneWay}"
      SelectedItem ="{Binding PlacementTarget.Tag.SelectedOne, RelativeSource={RelativeSource AncestorType=Window}}"
      SelectionMode="Single">
<ListView.View>...</ListView.View>
<ContextMenu Name="cmListViewVersion">
      <MenuItem Name="mnuNewVersion"
            Header="New"  
            Command="{Binding PlacementTarget.Tag.NewVersionCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"  
            CommandParameter="{Binding SelectedItem}">
      </MenuItem>
</ContextMenu>
</ListView>

<ListView Name="VersionView" 
                                          IsSynchronizedWithCurrentItem="True"
                                          Tag = "{Binding DataContext, ElementName = WindowMain}"
                                          ItemsSource="{Binding Path=VersionList, Mode=OneWay}"
                                          DataContext="{Binding SelectedItem, ElementName=GroupView, Mode=OneWay}"
                                          SelectionMode="Single"
                                          
                                          SelectedItem="{Binding DataContext.SelectedOne, ElementName = WindowMain}"
                                >
...

CommandParameter="{Binding}"