Hi Thomas,

As far as I am aware, I think there is no ruler widget but you can create new / modify existing widget according to your requirements.

Some helpful links below;

https://academy.mendix.com/link/path/108/Build-a-Pluggable-Widget

https://academy.mendix.com/link/path/45/Building-Custom-Widgets-(Micro-Learning)

https://docs.mendix.com/howto/extensibility/build-native-widget#3-3-4-content-property

https://docs.mendix.com/howto/extensibility/widget-development#2-prerequisites

Hope this helps!