Upgraded from U19 to U20 and ran it for the first time, and tried to change a setup by dragging a slider (gear ratio or something). It didn't work, neither did any other slider. Also right-clicking on them didn't work, only the arrows. As I remembered another bug (ctrl-shift) that was solved by going into multiplayer and back, I did the same thing, and the sliders worked again..
Don't know if this was a patch-specifig bug or something, but thought I should report it.