if (target != null)
target.beginCompoundChange();
if (viewer instanceof IEditingSupportRegistry) {
IEditingSupportRegistry registry= (IEditingSupportRegistry) viewer;
registry.register(helper);
}
if (p instanceof ICompletionProposalExtension2 && viewer != null) {
ICompletionProposalExtension2 e= (ICompletionProposalExtension2) p;