Popup.AllowsTransparency Property

A Popup control can only contain transparent content when the application runs with full trust. An application that runs with full trust has complete access to system resources and is typically installed on the local system. For more information, seeSecurity (WPF).

This property cannot be set to true when the Popup is hosted in a XAML browser application (XBAP).

If the AllowsTransparency property is set to true in an application that does not run in full trust, the AllowsTransparency property value is changed to false. An application that is hosted in a browser is an example of an application that does not run in full trust.

The following example shows how to set the AllowsTransparency property on a Popup control.

myPopup.AllowsTransparency = true;

<DockPanel  Width="500" Background="Aqua">
  <Popup Placement="Center" PlacementRectangle="0,0,30,50"  
          IsOpen ="True" AllowsTransparency="True"
          PopupAnimation="Fade">
    <TextBlock Background="Purple">Popup Text</TextBlock>
  </Popup>
</DockPanel>

.NET Framework

.NET Framework Client Profile

• SecurityPermission  

  for setting this property to true. Associated enumeration: UnmanagedCode

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference