RibbonWindow margins on startup when maximized

Hi,

I've observed an unexpected behavior when the startup window is set as
WindowState="maximized", i.e. the application is set to start in maximized state.

The window seem to have a negative margin: it seems to start a couple of pixels outside of the available area (it appears to be "behind" the Windows bar).
When I resize the window and re-maximize it, then it becomes normal.
I've seen this with our project, but I noticed the sample project also behaves that way.

This is the window as the application starts while this is after the window has been scaled down and then re-maximized. If you switch quickly between the two you can easily see what I mean.

Thanks, bye
Francesco