karus

I am answering to my own question as I could not wait too long for a support answer.

The issue came for the interaction between the Massive Dynamic theme and the plugin Carousel Slider. The plugin is using the library called Magnific-Popup which adding some style to the html and body tag when it popups and remove it when closing.
However for some theme like Massive Dynamic which has by default some style to the html tap like Overflow: auto, the fact to be removed by Magnific-Popup make other class which might have Overflow: hidden to be active then.

To solve the problem without changing the theme, I modified the file “carousel-slider/assets/lib/magnific-popup/jquery.magnific-popup.js” like this :

from (line 421):

if(mfp.fixedContentPos) {
   var windowStyles = {marginRight: ''};
   if(mfp.isIE7) {
	$('body, html').css('overflow', '');
   } else {
	windowStyles.overflow = '';
   }
   $('html').css(windowStyles);
 }

to :

if(mfp.fixedContentPos) {
   var windowStyles = {marginRight: ''};
   if(mfp.isIE7) {
	$('body, html').css('overflow', 'auto');
   } else {
	windowStyles.overflow = 'auto';
   }
   $('html').css(windowStyles);
 }

Hope that might help someone
Regards
David