No, as I've written, their main idea was to provide mixed mode. On top of which you can provide a widget set. Something like GKS or Phigs was true retained mode graphics, and toolkits like AppKit were reactions to the limitations of those types of mechanisms.
There is a reason the Mac had QuickDraw and NeXT had DPS and not GKS or Phigs. Well, many reasons, but one was that the limitations of pure retained mode graphics systems were well known.
> they have escape hatches to draw your own widgets when needed.
Yes and no. While you can view them as escape hatches if you're primarily doing widget-only programming, they aren't really escape hatches as the entire system is based on / built on them. Just like in Objective-C, objc_msgSend() is not the escape hatch, it is both the basis for all messaging and it enables the escape hatch, which is -forwardInvocation:. Similarly -drawRect:: and responder handling: they are the basis on which everything else is built. Since they are exposed, that means you can build your own views/widgets as peers to the ones provided.
> Almost any book on GUI programming on Cocoa ...primarily focuses on the available widgets
The books I learned AppKit with focused on creating a custom view, drawing with DPS and pswrap, handling mouse events and the responder chain.
(a) not convinced that's true
(b) not relevant
> But their main idea wasn't "immediate mode",
No, as I've written, their main idea was to provide mixed mode. On top of which you can provide a widget set. Something like GKS or Phigs was true retained mode graphics, and toolkits like AppKit were reactions to the limitations of those types of mechanisms.
There is a reason the Mac had QuickDraw and NeXT had DPS and not GKS or Phigs. Well, many reasons, but one was that the limitations of pure retained mode graphics systems were well known.
> they have escape hatches to draw your own widgets when needed.
Yes and no. While you can view them as escape hatches if you're primarily doing widget-only programming, they aren't really escape hatches as the entire system is based on / built on them. Just like in Objective-C, objc_msgSend() is not the escape hatch, it is both the basis for all messaging and it enables the escape hatch, which is -forwardInvocation:. Similarly -drawRect:: and responder handling: they are the basis on which everything else is built. Since they are exposed, that means you can build your own views/widgets as peers to the ones provided.
> Almost any book on GUI programming on Cocoa ...primarily focuses on the available widgets
The books I learned AppKit with focused on creating a custom view, drawing with DPS and pswrap, handling mouse events and the responder chain.