To change to a hidden decor you keep CTRL+ALT+SHIFT pressed and click on the BeMenu of the Deskbar. Then you’ll find an entry “Window decor” that offers the looks of BeOS, AmigaOS, MacOS 8 and Windows 95/98.
These decors are hardcoded so it’d be extremely difficult to further tweak them (I imagine a hex editor and lots of time could do it however…).
One more hidden feature: Again, keep CTRL+ALT+SHIFT pressed, click on the BeMenu of the Deskbar and choose “About BeOS”. Now there’s a bar with a rough approximation of your memory usage.
HAND