Allow for ruler to act as a fixed full width reference line

[LarsOevlisen]

Description of the new feature / enhancement

Allow for the ruler to act as a full width reference line, maybe with simple ruler markings along the bottom.

Scenario when this would be used?

The ruler is currently a great tool and candidate for a "PowerToy". Still, I sometimes find myself in need of a fixed full width reference line, e.g., when wanting to compare aspects within certain graphics or diagrams (this is sometimes useful for comparing levels in certain charts where the raw data is not available).

Supporting information

No response

[dam5s]

I would like this feature as well and I think it should also be possible to add a vertical line as well. Similar to how guides work on xScope for MacOS.