public void PrevIllust()
{
if (this is HistoryPage && HistoryItems.ItemsCount > 0)
{
if (HistoryItems.IsCurrentFirst)
{
HistoryItems.MoveCurrentToLast();
}
else
{
HistoryItems.MoveCurrentToPrevious();
}
HistoryItems.ScrollIntoView(HistoryItems.SelectedItem);
}
}