Jade is an Alternative Development Environment (IDE) for GemStone/S that runs on Microsoft Windows. This screencast gives a brief demo from 2013.
Jade is built in (and inspired by) Dolphin Smalltalk from Object-Arts.
The Releases page contains links to a zip file with the executable and supporting libraries.
Older versions are available using the instructions here.
Jade runs pretty well under Wine and a pre-built Mac app is available here. It may be out-of-date, so you can use “Show Package Contents” and then update "drive_c/Program Files/Jade” with items obtained from here.
To install Jade in Dolphin 7, follow these steps: