Bug 63155 [Refactoring] no user feedback when error during implicit refactoring triggered by drag'n'drop
org.eclipse.ltk.core.refactoring/src/org/eclipse/ltk/core/refactoring/participants/ProcessorBasedRefactoring.java
pm.beginTask("", 9); 
		pm.setTaskName(RefactoringCoreMessages.getString("ProcessorBasedRefactoring.final_conditions")); 
		
		result.merge(getProcessor().checkFinalConditions(new SubProgressMonitor(pm, 5), context));
		if (result.hasFatalError()) {
			pm.done();
			return result;
		}
		if (pm.isCanceled())
			throw new OperationCanceledException();
		
		fParticipants= getProcessor().loadParticipants(result, fSharedParticipants);
		if (fParticipants == null) 
			fParticipants= EMPTY_PARTICIPANTS;
		if (result.hasFatalError()) {
			pm.done();
			return result;
		}
		IProgressMonitor sm= new SubProgressMonitor(pm, 2);
		sm.beginTask("", fParticipants.length); 
		for (int i= 0; i < fParticipants.length && !result.hasFatalError(); i++) {
			result.merge(fParticipants[i].checkConditions(new SubProgressMonitor(sm, 1), context));
			if (sm.isCanceled())
				throw new OperationCanceledException();
		}
		sm.done();
		if (result.hasFatalError()) {
			pm.done();
			return result;
		}