One of the unique things about Smalltalk is that the GUI for defining, accessing and modifying classes is an integral part of the language. You write code to i

One of the unique things about Smalltalk is that the GUI for defining, accessing and modifying classes is an integral part of the language. You write code to implement your methods, but the structure of your application is defined more or less with pointing and clicking (and you can use the same UI for inspecting the implementation of the language itself, or at least parts of it). As far as I understand GNU Smalltalk replaced this with some ad hoc syntax for defining classes by editing text files.