不透明度未应用于WPF Popup控件

Question

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;

How to do it?

Answer 1

You should Enable Popup to have Transparency. Add following line of code.

popUpControl.AllowsTransparency=true;

Answer 2

You need to set the opacity on the popup content.
So for your button have

popUp.Child = new Button() 
{
    Width = 300,
    Height = 50,
    Background = Brushes.Gray,
    Opacity = 0.5 // set opacity here
};