Check length of screen contents for lines > 80 chars

[ghost]

Frank would like to see this in the stylesheets (too) but it definitely should be available in the style checker.

[tomschr]

This is a good idea! 👍But isn't it more useful to do it in our stylesheets?

[ghost]

Style checker definitely needs it, but stylesheets won't hurt, imo. But most people will ignore this (or never see this) if it only comes from the stylesheets.