I even located a registry entry at HK_LOCAL_MACHINE\SOFTWARE\WoW6432Node\GoG.com\GOGGABRIELKNIGHT3 with a "MAXIMIZED" string like that had "max" as the value. Tried deleting it to match some of the other GOG game entries, but it did nothing, and I restored it.
I finally got it to run in window mode by changing the desktop color depth to 16-bit instead of 32-bit. I tested both the "Primary Display Driver" and "Software Renderer" settings with 640x480, 800x600 and 1024x768, but nothing changed with the laptop. I also attempted the "ATI Radeon HD 4800 Series" option, but it crashed the game (never does that in 32-bit), and upon restarting it was in full screen mode. Changing the renderer to Primary Display Driver while in-game put me back into window mode again.
So, no dice.
(The WinXP computer downstairs will be available later, and I shall try window mode with it when I can.)
