The shop keeper text says to click to continue, but you need to press space and the jumping moves the position of the upgrade grid. It would also be nice if it remembered the position and zoom settings.
The smelter needs more speed upgrades. There is too much waiting for hiher level upgrades. Also, activating the smelter should fill and empty in one click. You can't take gold out if you have any ore left and the smelter is not full.