Please tell me how to engage column mode editing on a Mac? Shift+command does not seem to work. I was trying to explain this useful feature to a new user and realized that the documentation does not make this clear, nor does set keyboard short cuts. I.e. it is a useful feature but not immediately obvious how you get it it on a Mac. The doc reproduced below does not help either. It would be useful during new user onboarding it this were a settable keyboard combination that could be easily found and set as needed.
Column mode editing (rectangular selections)
There is basic support for column mode editing. To use it, create a rectangular selection by holding down the Control and Shift keys (or Alt and Shift on Windows) while selecting some text. Once a rectangular selection exists you can start editing the text within this selection and the modifications will be done for every line in the selection.
It is also possible to create a zero-column selection - this is useful to insert text on multiple lines.