Mac: Can't select text in any term window after running a termui app for a while

I've written a new app using termui, which is marvellous. Unfortunately I've found that I can't select text with the mouse in any terminal window after running termui for a while. This has happened to two people so far, both using Macs. The problem doesn't disappear when the app is terminated - you need to quit out of term and restart.

Any ideas? What information can I give you?

Start by reproducing the problem on macOS: run a termui app for a while, then try selecting text in other terminal windows and after terminating the app. Collect the terminal, macOS, and termui app details requested by the report; done means terminal text selection continues to work without restarting the terminal.

Written by the indexing model from the issue text.