fix for multi select cates and tags

app/controllers/admin/page_parts_controller.rb

@@ -73,7 +73,7 @@ class Admin::PagePartsController < ApplicationController
       params[:page_part][:category] = []
     end
 
-    params[:page_part][:widget_field].each{|t| t[2] = (t[2]=="true" ? true : false )}
+    params[:page_part][:widget_field].each{|t| t[2] = (t[2]=="true" ? true : false )} if !params[:page_part][:widget_field].blank?
 
     if @part.update_attributes(params[:page_part])
       set_children_sub_menu(@part) if @part.public_r_tag && @part.public_r_tag.eql?('sub_menu')