It seems that CaptureMouse is behaving differently in WPF and Silverlight, in that in the former one it immediately calls OnLostMouseCapture at a Visual, whereas in Silverlight it doesn’t get called if the element didn’t have the mouse capture already (btw, in Silverlight that method is at a UIElement – there is no Visual ...

While stepping through “ShowDialog()” method of OpenFileDialog with Visual Studio 2010 debugger, at the Silverlight code pictured below (for loading a ClipFlair window’s stored options), I got a “Dialogs must be user-initiated” exception. Same behaviour will be shown with SaveFileDialog too, every time you try to step through the “ShowDialog()” ...