Two-finger trackpad scroll in Slack Windows desktop app and Gmail

You have a Dell laptop running Windows.

Two-finger scroll works in most websites, but sometimes doesn't in Google Chrome (e.g. in Gmail), and never works in the Slack desktop app.

The solution appears to be here, although note that it did not work for me, but then after a reboot some time later, it worked.  So maybe you'll need to fully shut down Google Chrome and restart it, or restart the entire computer, after making the change.

I am delighted to now be able to scroll easily using two-finger scrolling on the laptop's built-in trackpad, in the Slack desktop app, and in Gmail.