Label label = new Label(container, SWT.NONE);
label.setText(Messages.FromMapWizardPage_Map);
_viewer = new TreeViewer(container, SWT.BORDER | SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
final ObservableListTreeContentProvider content = new ObservableListTreeContentProvider(
BeanProperties.list("allChildren", Folder.class).listFactory(), //$NON-NLS-1$
new FolderStructureAdvisor());
_viewer.setContentProvider(content);
_viewer.setLabelProvider(new ScannedMapsLabelProvider());
_viewer.setUseHashlookup(true);
_viewer.setInput(CalibratorPlugin.getBL().getTreeRoot());
_viewer.addSelectionChangedListener(new ISelectionChangedListener() {