20 Years of Photoshop
benwiggy writes "Photoshop turned 20 on 10th February 2010. Here's an excellent history, including how the Knoll family created one of the biggest apps of all time. The article also has screenshots of the workspace through the versions."
Yep, no multiple windows throughout its history. Just the usual MDI with panels interface.
That says something from the industry's standard to the would-be competitors.