How to apply custom theme on extension app

Hi ,

I am trying to apply custom theme on extended app.

I created a new extension of standard app using SAP Web IDE, Default theme defined in  index.html is "sap_bluecrystal" now if user will go to Fiori launch pad-> user preferences and change theme to some new custom theme, How we can apply any new custom theme to extension project automatically?

Please suggest.

Thanks!