This type of menu is akin to those provided by the taskbars of desktop environments such as Xfce or LXDE. Automatically updating on-the-fly, this type of menu can be powerful and very convenient. It may also be possible to add custom categories and menu entries; read the documentation for your intended dynamic menu to determine if and how this can be done.
A menu generator will have to be executed
from the ~/.config/openbox/menu.xml file.