There was a browser that worked on Squeak 3, Whisker, that had some of these attributes. I used it up until it became unsupported. It took a little getting used to as its primary orientation was horizontal, but in the age of widescreen monitors that is an advantage.

Wiki description: https://wiki.squeak.org/squeak/1993

Archive of its homepage. Has an image of the browser in use. https://web.archive.org/web/20070228113449/http://www.mindsp...

Yes, Whisker is exactly what came to mind for me as well.

I don't currently use Smalltalk, most of my code is now written (and read) in vscode. The means available for showing the context around the code under consideration (splitting and resizing panes, hunting through lists of tabs, scrolling around) feel pretty crude by comparison.