Hi,
The trick is to use conditionnal using
#if CSHTML5
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using System.Windows.Browser;
#else
using System.Windows.Threading;
using System.Windows.Controls;
using System.Windows;
#endif
and it works great.
Remi