$.fn.modal.Constructor.prototype.enforceFocus = function () {

      modal_this = this

      $(document).on('focusin.modal', function (e) {

         if (modal_this.$element[0] !== e.target && !modal_this.$element.has(e.target).length

               // add whatever conditions you need here:

            &&

            !$(e.target.parentNode).hasClass('cke_dialog_ui_input_select') && !$(e.target.parentNode).hasClass('cke_dialog_ui_input_text')) {

            modal_this.$element.focus()

         }

      })

  };