VSE has had a complicated history which starts with a product called Digitalk Smalltalk/V that ran from a DOS prompt and provided a windowing environment.
They can also enhance the functionality of the main VSE Smalltalk system and use that within the PARTS Workbench.
The natural style of using this system tends to lead to many links and scripts - it is not based around the idea of 'model' (as used in 'Model–View–Controller' approaches common in many Smalltalks as well as in other languages).
It has an immediacy that makes it very good for introductory teaching and for rapidly implementing programs with visual interfaces.
A result of the complex history is that the copyright and licensing situation is unclear and a typical recent VSE development environment is made up of many elements many of which were developed by third parties and sold separately but are now included with the distribution.