Openbox disable Alt+F4
With credit to here, you can disable the Alt+F4 combination in Openbox by editing .config/openbox/lxde-rc.xml with code similar to:
<keybind key="A-F4">
<action name="If">
<title>* Chromium</title>
<then>
<!-- Do nothing when Chrome is the active window -->
</then>
<else>
<!-- Do nothing in other cases as well -->
</else>
</action>
</keybind>