The Scala debugger needs to be plugged in the existing launch configurations code, to be available. The code is slightly different for each launch configuration type, and usually require to add a dependency to the plugin containing the launch configuration.
We need to add it to the JUnit launcher because we already depend on it.
For the other launchers, the simplest might be to create a new plugin with optional dependencies to the launch configurations, and the specific implementations. It needs to be in a different project, to avoid to add too much overhead to the main scala-ide project.
Luc