On 17 Dec 2021, at 13:06, Graham Heath wrote:

Duplicate line will throw

ruby: warning: -K is specified; […]

when you have 2 cursors.

Ah, that's why. With multiple cursors I get that error, and if I remove -K, then I get the undefined method '+' for nil:NilClass error.

I can live with this.

Thanks for helping the world make sense again.