Imo, the problem with the 4-pane browsers are: 1 - The left-most 'package' pane is a flat list. And there are 10K + classes in e.g. Pharo. There are 900+ (!) packages in Pharo, in the pane, so its not easy to scroll through. This is solved 'manually' by have a hierarchical naming of packages. I think this pane should just have tree view. 2 - When developing an app, you may be working on classes in multiple packages. You want to have 'project' view with a simple way of switching between them, without having 10+ system browser windows open, like shown in the article. Dolphin Smalltalk has implemented this concept. Shameless plug: SmallJS (https://small-js.org) has these too..

Extending that, an outliner can be a great way to deal with this stuff. The problem becomes the self-referential nature of OO systems. Outliners are good when you get to the method of interest, but then you have the problem of browsing senders and implementers.

Still, there's nothing worse than a Smalltalk without a class category list. Smalltalk/MT, for example, just had a class hierarchy browser, and the category class member variable was left blank. I found it very hard to know where to start looking for behavior.

While I agree that the package column has room for improvement, some of the 'largesse' can be handled by the search field at the bottom of it, and once you get to doing something serious you could set up your own image and ditch a lot or most of the standard distribution.

I think I'd prefer a pane view over a tree view because the higher levels retain their scroll position even as I browse beneath. Is there a similar UX possible for tree views?