For some structures existing pages can be added per drag and drop. However new items cannot be selected with drag and drop for some other structures in the same wiki. I spent many hours to find a difference between the two structure types. Up to now, the main difference is the size. Large structures, which do not fit into the browser screen, do not work. For medium size structures, I found a work around: Drag and drop is possible, when the browser's zoom factor is set to value that shows the whole wiki page in the browser window.
Pages can be moved within a structure, but it is not possible to add existing pages.
Is there a concept for managing larger structures?