In file /usr/share/X11/xkb/symbols/br of package xkeyboard-config-2.16-1.fc23.noarch there is a keymap called thinkpad that correct the problem of the slash/question key being interpreted as Right Control instead on some Thinkpad models. However, this layout is not available to the user because it is not included in the index files: /usr/share/X11/xkb/rules/{evdev.lst, evdev.xml, base.lst, base,xml}. When the layout is added to these files, it automatically becomes available in KDE/Gnome/Xfce keyboard settings.
xkeyboard-config-2.16-2.fc23 has been submitted as an update to Fedora 23. https://bodhi.fedoraproject.org/updates/FEDORA-2015-934f79dc89
xkeyboard-config-2.16-2.fc23 has been pushed to the Fedora 23 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2015-934f79dc89
xkeyboard-config-2.16-2.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.