It's not just the windows - it's a host of details. I spent many hours staring at that original monochrome Macintosh interface, and the homage here is obvious.
- Single menu bar at the top of the screen
- System logo menu to the left of the application menus
- Clock on the right side of the menu bar
- Desktop icons arranged top to bottom on the right
- Trash icon in the bottom right
- Same medium grey dithered desktop background
- Same light grey dithered scroll bar fill
- Horizontal stripe pattern in the window title bar
- Centered window title text
- Identical window zoom icon placed in identical location
- Identical file browser window header and column arrangement
The system font is different (likely because it is smaller), the scroll arrows are different, and the Mac never had accelerator-key underlines in its menus, but it is very, very clear that the people designing this interface knew the classic Mac OS well and have purposefully based their design on it.
I had little idea what it would look like when I first started experimenting with window managers, but it was Paul Fisher's initial mock-ups and font designs which steered things towards the Mac "look". I was just happy to have some guidance and help regarding the visuals, since I was too busy with code to design fonts. But it's clear that Paul took a lot of design cues from System 1-7, and this led me to study those same GUIs closely, although I diverged from that when it came to the tab controls on the Profiler (task manager). But yeah: homage it is, and it's also practical, since it looks good at such a low resolution.
Compare to e.g. AmigaOS or Atari's own GEM for the ST/TT line and you'll see what he means. It's much closer to the original MacOS style than the main alternatives of the period.
