- Earlier 'Preview' code was using bootstrap-modal. It was showing what ever given to begin with. It was not picking up changes done to timeline events. I tried a lot of things to 'destroy' it on closing and recreate a frsh one while showing. But it did not work.
 - So finally I threw away that and used 'prettyPhoto' plugin/gem to give preview popup. Wasted a hell lot of time because its documentation did not mention the javascript function to be invoked to pop it out. !@#!@#$@#$$##@$%%$

Now 'Preview' works fine.