Hans-Martin,
I was completely mistaken. SchemeScript 1.2.15 does depend on org.eclipse.pde. I don't remember why and the code does not rely on org.eclipse.pde, so this was probably the result of a test I did and forgot to remove the dependency. Sorry about that.
The solution to this problem is, as you did, download and Eclipse version that provides the pde (Plugin Development Environment).
Hi,
which version of SchemeScript did you try to download? I'm quite surprised, because SchemeScript has never depended on org.eclipse.pde.ui.
I am aware that there were a number of problems with the mirror sites lately for Eclipse 3.5.1.
