Since v18.104.22.1687 new setting for the blog is added: Grouping of Multibox.
Enabled by default (to keep previous blog multibox handling), this option can be found in the Online Administration section of the blog, Settings tab.
When this is enabled, all element that have multibox and are from the same type * will be grouped into same box with navigation to loop among them.
When this is disabled, every multibox element will pop-up in separate box and no navigation among the other similar elements will be possible.
*Different types of multibox elements (image thumbnails, pure links, etc) are grouped separately from each other by the multibox handler. In other words - you can put both thumbnail and a link into same box and navigate through them.