Ten years ago it was Delphi7. It was the last great version in a series of great versions (1, 3, 5, and 6). It was a real tool, when you wanted to do something, you just find what you want, put it there and concentrate on the final objective. When something more was needed, again it was just a matter of intuitively find how to extend. When something was not clear, hit F1 and the help will clarify the things.
Since then the UI tools had evolved, but not on the same direction. Today to do a UI in Java, for even some simple forms, is a matter of learning layouts, draw first on paper, think at each step what margins should you put, how the form will size, fill some pages of code with just layout data, and ending up testing and retesting with different colors for panels to see what is the result. It is true that the layouts are very powerful tools, on which sophisticated UIs can be created, but are unintuitive and difficult to be done in visual editors. So you end up spending time doing it, and even worst, you have to learn the inner workings of something that should only be a tool you use to produce the UI you have in mind.
On the other hand, on the non-visual part, Delphi7 had grown old, but Java is doing great on the productivity of the language and the number and quality of libraries. So I end up wanted to do something in Java, but then on the UI and general application development missing Delphi7 a lot, to the point that I want to do the UI in Delphi7, and the coding in Java.
Eclipse is a great tool; the debug is good and is quite fast and intuitive. What it is missing are the parts where Delphi7 was great, intuitive and fast UI visual editor and friendly component library. IusCL was created to address that. SWT already is some sort of VCL, meaning a library on top of the Windows API written in a different language that C. But it is on a different idea, on the SmallTalk/Swing path, with layouts, listeners, and numerical constants. So on top of SWT, build a layer to make it more like Delphi7, with properties, events and form serialization built-in. Then in an Eclipse plug-in, have an editor as close as possible to the one in Delphi7. This way we can have the best of both worlds, working in Java writing classes and implementing the application business, and on the presentation part, working in Java but with a Delphi7 feeling.
So, the main objective of this project is to have in Java/Eclipse the same feeling as in Delphi7, everything to be just where you would think it is, not to think too much about how the tool is working, but just use the tool to do what you need to do.
The project is generally based on Delphi7, so as well as Delphi7 is still used today in its original form, IusCL also will probably going to have a "final version" that will not change and only new components will be added.