Allow downgrade of ghosts

For example, a tier 2 pipe ghost can be upgraded to tier 3 via the upgrade button, but there is no downgrade button to downgrade to tier 1. You either have to delete the pipe and recreate it at tier 1, or use the upgrade tool, select the pipe twice (first upgrade to tier 3 before the dialog opens), select tier 1 from the drop down and click the replace button. This is very cumbersome. A simple downgrade button next to the upgrade button would be helpful.

If you mouseover the upgrade button, there's a downgrade button in the tooltip- both on ghosts, and constructed pipes. You can also box-select with the Upgrade tool, and it'll always ask what you want to upgrade it to, rather than only going to the next tier.

But yes, a "downgrade" version of the Upgrade tool, even if just as a modifier key, would be nice to have.

There's a tooltip!! Thanks.
I guess "Discoverable UI" also means you may just not discover everything and miss it.

A simple click with modifier would be the best, of course.