I have a number of machines (hardware and VMs) running CentOS 7. I all cases firewall-config is not functional.
First, the service check boxes are not functional. When you click on one, it don't change to "checked", and nothing changes on the firewall. However you do see a "Changes applied"
Sometimes, f you go to permanent mode and attempt to edit a zone, the whole desktop locks up as soon as you click on the default target dropdown.
When I run firewall-config from the command line I see the following:
--------------------------
org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.NetworkManager was not provided by any .service files
(firewall-config:5079): Gtk-CRITICAL **: gtk_tree_view_get_path_at_pos: assertion 'tree_view != NULL' failed
-------------------------- with the second line repeating many times and often while attempting to interact with the GUI.
We don't use NetworkManager except on laptops, and so do not install it. Though we do install NetworkManager-glib, if only because some packages require it.
After seeing a similar bug on the RHEL I also installed NetworkManager-libnm, but that did not make a difference. That RHEL bug also mentioned this problem only occurs on KDE, and not Gnome. And we only install KDE when a GUI is required, or desired.
Emmett