'3D' UI elements were introduced later in AmigaOS2.0, and I remember how the user interface style guide made a big fuzz about how UI elements that appear raised are supposed to be clickable while flat or recessed elements shall be used for non-interactive or disabled UI elements which cannot be interacted with.
Actually this site is a pretty awesome collection of operating system UIs. BeOS still looks nice, almost like retro-modern pixel-art.
Older UIs like the Amiga OS one suffered from an even more limited pallet, and even worse typography.
I used BeOS as my main OS for a while and really liked it - it was very snappy and felt more "homey" (that is, more like classic MacOS) than early OSX versions did. (The browser, NetPositive, was absolutely awful though).
For instance: AmigaOS 1.3 (notice in the bottom-most screenshot how the buttons don't have '3D edges':
http://toastytech.com/guis/amiga1.html
'3D' UI elements were introduced later in AmigaOS2.0, and I remember how the user interface style guide made a big fuzz about how UI elements that appear raised are supposed to be clickable while flat or recessed elements shall be used for non-interactive or disabled UI elements which cannot be interacted with.
Actually this site is a pretty awesome collection of operating system UIs. BeOS still looks nice, almost like retro-modern pixel-art.