In Winforms you can say (with some slightly unexpected behaviour)
if (DesignMode)
{
// Do something that only happens on Design mode
}
In WPF, you've got
if (DesignerProperties.GetIsInDesignMode(this))
{
// Do something that only happens on Design mode
}
But I'm struggling to find a similar option for the slimmed down PCL world that is Universal apps?