If the ScreenRuler colour overlay does not span over all of your monitors, read below for instructions on how to fix this. This is related to ClaroRead not reappearing after being minimised.
- Click on the Apple logo in the top left of your screen
- Select System Preferences
- Select Mission Control
- Uncheck Displays have separate Spaces
- Log off or restart your computer
- Launch ScreenRuler – the ruler window will now span over all your displays