Gets or sets a value that indicates whether the application window is always displayed in front of other windows.
Assembly: System.Windows (in System.Windows.dll)
The application is not running outside the browser.
The current thread is not the user interface (UI) thread.
You can set this property only in the following cases:
In response to a user-initiated action, for example, in a button Click event handler.
In a trusted application.
If multiple applications have main windows with values of true, the actual topmost window is the one most recently active.
In Silverlight 5, trusted, out-of-browser applications can create multiple Window instances and manipulate them programmatically. However, the property is meaningful only for the Application.MainWindow instance.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.