drag and drop chrome or firefox

Hello, I am just starting with opigno and lms and drupal.... (the perfect newbie) I am following the user guide andd trying things around just to understand what is feasable with opigno which look like the best tool for my project I cannot create a slide with drag and drop question because on chrome the popup does not show and on firefox the popup is not readable (a small part of it appears under the picture area but Is there a version i should use for chome and firefox or a module/plugin/add-on or setting I should use (I am using linux mint) Best regards, Bidule