No, TIO already supports languages that can do that and more. All user-supplied code is executed in a sandbox, without internet access and without the ability to make permanenet changes to the system.
@Dennis Oh, sorry. I was looking for some Octave code and didn't notice. (Or I could say it's so natural as it is now that I hadn't noticed) :-P I think it's better now
@JamesHolderness OK, I sandboxed the Befunge 98 interpreter. Thanks for bringing this up! There are still security issues, but at least it should be denied network access and file system writes now. v1 is mostly built on hopes and prayers. There will be no such issues on Nexus.
Not really CSS. Focusing the code textarea checks if it should be resized to accommodate its content, and that makes it jump. I'll try to find a better way to handle this.