Bug 11437 jar packager: no error message but buttons disabled
20020314 on the 'jar manifest' wizard page, if you select to use existing manifest file there's no error message but next and finish are disabled user should be informed what to do to make the wizard happy
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarManifestWizardPage.java
*/	
	protected ElementTreeSelectionDialog createWorkspaceFileSelectionDialog(String title, String message) {
		int labelFlags= JavaElementLabelProvider.SHOW_BASICS
						| JavaElementLabelProvider.SHOW_OVERLAY_ICONS
						| JavaElementLabelProvider.SHOW_SMALL_ICONS;
		ITreeContentProvider contentProvider= new JavaElementContentProvider();
		ILabelProvider labelProvider= new JavaElementLabelProvider(labelFlags);
		ElementTreeSelectionDialog dialog= new ElementTreeSelectionDialog(getShell(), labelProvider, contentProvider); 
		dialog.setAllowMultiple(false);
		dialog.setValidator(new ISelectionValidator() {
			public IStatus validate(Object[] selection) {
				StatusInfo res= new StatusInfo();
				
				if (selection.length == 1 && (selection[0] instanceof IFile))
					res.setOK();
				else
					res.setError(""); 
				return res;
			}
		});
		dialog.addFilter(new EmptyInnerPackageFilter());
		dialog.addFilter(new LibraryFilter());
		dialog.setTitle(title);
		dialog.setMessage(message);
		dialog.setStatusLineAboveButtons(true);
		dialog.setInput(JavaCore.create(JavaPlugin.getDefault().getWorkspace().getRoot()));
		return dialog;
	}
}