}
// create the treeViewer (list of possible validations (plugins) + prepared tests)
treeViewer = new CheckboxTreeViewer(comp);
treeViewer.setLabelProvider(new ValidationTreeLabelProvider());
treeViewer.setSorter(new WorkbenchViewerSorter());
contentProvider = new ValidationTreeContentProvider();
treeViewer.setContentProvider(contentProvider);
treeViewer.addCheckStateListener(new ICheckStateListener(){
public void checkStateChanged( CheckStateChangedEvent event ) {
Object element = event.getElement();