Bug 8476 JAR Packager: Make main class field editable
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;
	}
}