Change Default Drop Zone For Entire Theme

main.js

AUI().ready(
     function(A) {
          A.Do.before(function(option) {
               if (!option.placeHolder) {
                    option.placeHolder = A.Node.create('<div class="loading-animation"></div>');
               }
               option.placeHolder.prependTo('TARGETED-COLUMN-ID');
           }, Liferay.Portlet, 'add', Liferay.Portlet);
     }
);

This is great. Thanks for the snippet!