I am still able to load the locomotive with loaders and start the train with locomotive tracks. However, the actual GUI buttons do not respond.

I believe it is not yet implemented.

My apologies then. Closing out then.

Uh I thought it was working.

Just spent an hour trying to confirm it's not a mod interaction issue. (Used a barebones modpack I threw together.) None of the buttons nor inventory slots will do anything. The only interaction I was able to do was right click a water can from forestry on the steam locomotive and the water will show up in the trains water meter.