Command + F3 Border Beneath Menu Bar

[VFN]

When moving to the desktop using command + F3 the very bottom border of the page of the program that was open appears beneath the Menu bar. It's useful in that you can click it and return to the window you were viewing but why the very bottom border? It confused me until I played with it for a while and realized what was transpiring. Seems like a useful feature poorly executed, unless it's some sort of malfunction of execution.

Any thoughts? I know I may one of the very few who use command + F3.

Thanks