You are on the wrong way, but thanks for your contribution ;) Just to clear it up:
I am talking about a custom work item Editor not about a Handler.
Its something like this:
public class MyWorkItemEditor extends EditBeanDialog<Work> implements WorkEditor{
public MyWorkItemEditor(Shell parentShell){
super(parentShell, "Title of my editor");
}
protected Control createDialogArea(Composite parent) {
//create my gui stuff
}
etc.
So I am talking about the GUI Dialog that pops up when clicking on a Service Task in the eclipse jbpm plugin =)