**Feature Request**
Brief title for your desired feature:
How would you like the feature to work?
A facility to overlay coloured shapes with varying transparency over the circuit diagram would be very useful!!!
Why is this feature important to you?
This feature is very useful for denoting blocks of circuitry or individual boards/assemblies and was used a great deal on Continental Service Manuals in the 1970s and 1980s!!!
Brand new interactions and interfaces. 
Easy to use and quick to get started. 
