public static DependencyObject GetPopupPlacementTarget(DependencyObject obj)
{
return (DependencyObject)obj.GetValue(PopupPlacementTargetProperty);
}

public static void SetPopupPlacementTarget(DependencyObject obj, DependencyObject value)
{
obj.SetValue(PopupPlacementTargetProperty, value);
}

/// <summary>
/// Popup位置更新
/// </summary>
public static readonly DependencyProperty PopupPlacementTargetProperty =
DependencyProperty.RegisterAttached("PopupPlacementTarget", typeof(DependencyObject), typeof(PopupHelper), new PropertyMetadata(null, OnPopupPlacementTargetChanged));

private static void OnPopupPlacementTargetChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (e.NewValue != null)
{
DependencyObject popupPopupPlacementTarget = e.NewValue as DependencyObject;
Popup pop = d as Popup;

if (popupPopupPlacementTarget != null)
{
Window w = Window.GetWindow(popupPopupPlacementTarget);
if (null != w)
{
w.LocationChanged += delegate
{
var offset = pop.HorizontalOffset;
pop.HorizontalOffset = offset + 1;
pop.HorizontalOffset = offset;
};
}
}
}
}

Popup位置隨窗口移動更新