Oh, I see.
This is most probably a limitation for the menus engine. I don't know if Pierre can do something for it, but I know that it isn't very advisable to do it. Usually, users expect to just expand the sub-menu.
Usually, assigning the categories is done through the Categories Pane - press F9 to focus it if it is visible. If it isn't visible show it first through View | Data Pane | Categories.
By pressing F9 you can quickly type some letters from the name of category to find it and assign it. You can also assign a key or a shortcut for each category. There are many ways to improve the assignment workflow. Using the menu will be quite difficult if your category tree grows.
Perhaps you need to read the full documentation here:
http://www.xnview.com/wiki/index.php/Ca ... _XnView_MP
m. Th.
- Dark Themed XnViewMP 1.7.1 64bit on Win11 x64 -