I'd like to suggest some improvements to the "not about Ubuntu" close reason.
"This is not about Ubuntu"
As it currently stands:
This is not about Ubuntu. Questions about other Linux distributions can be asked on Unix & Linux, those about Windows on Super User, those about Apple products on Ask Different and generic programming questions on Stack Overflow.
I'd suggest a link to the help/on-topic like so:
This is not about Ubuntu within the scope defined in the Help Center. [ .. ]
in order to clarify what topics are specifically allowed. The current text doesn't give much information about what is actually on topic. It's not a huge change, but should be significant to new users.
A while ago, there was this reason which was quite adequate:
Questions on Ask Ubuntu are expected to relate to Ubuntu within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here.