小编Sub*_*dev的帖子

Popup popUpControl = new Popup();

popUpControl.PlacementTarget = this; 
popUpControl.StaysOpen = true;
popUpControl.Child = new MyUserControl(); /// my user control 
popUpControl.Opacity = 0.5; // this code has no effect in the appearance of the popup
popUpControl.IsOpen = true;

怎么做？