Bug 174272 FileStoreEditorInput needs to be restorable
3.3 M5 The FileStoreEditorInput needs to restorable on startup. Therefore it needs to return an IPersistableElement and there needs to be an element factory.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDE.java
*            The <code>IFileStore</code> to test
	 * @return The workspace's <code>IFile</code> if it exists or
	 *         <code>null</code> if not
	 */
	private static IFile getWorkspaceFile(IFileStore fileStore) {
		IWorkspaceRoot root = ResourcesPlugin.getWorkspace().getRoot();
		IFile[] files = root.findFilesForLocationURI(fileStore.toURI());
		files = filterNonExistentFiles(files);
		if (files == null || files.length == 0)
			return null;
		
		return files[0];
	}
	/**
	 * Filter the incoming array of <code>IFile</code> elements by removing
	 * any that do not currently exist in the workspace.
	 * 
	 * @param files
	 *            The array of <code>IFile</code> elements
	 * @return The filtered array
	 */
	private static IFile[] filterNonExistentFiles(IFile[] files) {
		if (files == null)
			return null;
		int length = files.length;
		ArrayList existentFiles = new ArrayList(length);
		for (int i = 0; i < length; i++) {
			if (files[i].exists())
				existentFiles.add(files[i]);
		}