> "Do you have any plans to provide programming
language independent UI components"
Yes, in fact that is the main focus of LangEclipseIDE at the moment. However, being currently a one-man project, it's not as feature-full as JDT, nor will it be any time soon. But it's not too shabby either. This section has an overview of what UI functionality/components it currently provides:
https://github.com/bruno-medeiros/LangEclipseIDE/blob/master/README-LangEclipseIDE.md#functionality
So yeah, for example: content assist, code snippets ("Templates" in JDT lingo), preference pages for all that, outline and quick-outline (no hierarchical outline support though).
However, no Junit view, nor package explorer support. Well not for displaying Java-like flat packages at least, but there is some support for other Project Explorer extensions: stuff like project dependencies and (in an upcoming version) build targets. I dunno how well that applies to Scala though.
No code folding support either (DDT has that functionality, but it's crappy code copied from DLTK that hasn't yet been cleaned-up/refactored, and put into LangEclipseIDE).
One interesting thing that LangEclipseIDE has, that doesn't come from JDT or JDT-like IDEs, is functionality to help you integrate external, command-line tools to provide IDE functionality. For example in Goclipse, the outline is provided by an external parser (updated on the fly as the user types in the editor). Again dunno if that would apply well to Scala.
Sidenote: Funny enough, unlike JDT, the Goclipse outline is updated almost instantly as the user types, because there is no artificial delay to start the reconciler (I dunno why that delay is in JDT in the first place). Not that it matter much anyways - personally I haven't used the Outline view in ages, Quick-Outline is much more handy.