Standard Widget Extensions

Hello,
I have a problem with Standard Widget Extensions in Twenty Fourteen.
This plugin “Adds Sticky Sidebar”. But this feature doesn’t work properly with Secondary menu in left sidebar. In left sidebar I have menu, calendar widget and search. Once it works and in other situation it doesn’t work. E.g. in Firefox function doesn’t work. In Opera works, but only when I resize page on whole screen. How to fix this plugin or what I am doing wrong with it? Do you know other plugin like this?
Thanks for suggestions