I'm using WPF 4's (in .NET 4) ribbon control,
, in my application. The application menu and all sub-menu popups align as far left as possible, usually
outside the ribbon window. The expected location is that the application menu's left edge aligns with the ribbon window's left edge, and that sub-menu popups will align with the left edge of the right (usually recent items) content pane.
Here's a snippet of code showing the XAML of the RibbonWindow root element and the beginning of the ribbon declaration: