sorry, using the LXDE, but have same problems with other Linux distro's DE's, such as Mate and gnome. When you click on other instead of the default choice for an application to open with, the file manager opens up giving a plethora of personal files from which to choose an application. The dialog box should present the application menus, sometimes it does, often it does not.
A prime example is opening a .pdf file. If you choose other instead of the default reader, the file manager will open. The header bar at the top will say "choose an application" but all the choices are files, not applications.
I have not been able to locate a preferences setting that decides how to set this in PCLOS. Although, the behavior is more like a bug.