The startup, mValent, I was involved with before Eldarion built in many respects what could be described as an IDE for devops (before that role had that name—in fact we spent a lot of time trying to convince IT management that people in that role needed tools).
Our tool was built on Eclipse (not just an IDE but a framework for building IDEs). I was actually involving in the early days of the Eclipse Foundation.
Ten years ago, I was playing around with the Eclipse Graphical Editing Framework (GEF), which was a framework for building vector graphics editing tools (or similar functionality within other Eclipse-based tools). I think it had originally been designed as the basis for UML diagramming within Eclipse.
I was researching it partly for use within mValent (diagrams of PaaS stacks, etc, again before the term "PaaS" existed) but also for a generic pipeline processing tool I was working on personally called "River".
GEF was a pretty extreme example of design patterns (there was overlap between the Gang of Four and the Eclipse team plus have you often noticed how often drawing shapes is used in examples of OO and design patterns?). There wasn't just models, views and controllers but model, parts, figures, policies, commands and more—all loosely-coupled and extensible.