If the unlikely project to rewrite B4X was on the agenda, I believe the choice of Eclipse Framework would be obvious.
Eclipse? An IDE java? Not only it make IDE usable on all systems, but above all the advantage of a framework suited to the construction of IDE. In addition there is no need for installation, only a plug of the type zip or other.
A framework, stable, efficient, complete, ... of the editor, highlighting syntax, debugging, GEF for GUI, ... all framework for IDE development. More importantly, the heart of B4X is still the compiler, maybe it is written in java.
It is a real experience, in a company that has transformed a scripting language with mainframe communication. I carried out this project, the feasibility was demonstrated quite easily as the framework is complete and ... easy to implement. Simple ? No, but efficient. You don't write code like management of project, link with CvS or other addons, all the visual of an IDE is allready existing, ...
But hey, B4X exists and I believe that the priority is surely to others more ... pragmatic subjects.