You can copy all the block
"<Style TargetType="ListViewItem" x:Key="ListViewItemRevealStyle">
from generic.xaml
into
App.xaml
and you can add CornerRadius in each VisualState, like :
<Setter Target="Root.CornerRadius" Value="20" />
Then you set ItemContainerStyle in your ListView :
<ListView ItemContainerStyle ="{StaticResource ListViewItemRevealStyle}" >
A test with random colors and the new CornerRadius :