I work on two screens: laptop + standard on-desk monitor. Both have the same resolution (1920x1080), but laptop screen is smaller, obviously.

Now look what happens on the far-right side of the screen on CommandManager ribbon. When I have SW opened in a window (i.e. not full-screen) on the monitor it looks like this:

and when I move the window to my laptop screen this happens:

That's right - the icons that didn'f fit on the ribbon and are under the button disappeared.