Placing an axe in the new logging slot works just fine, walk up to a tree, and you can fell the tree. When you go to chop it into logs however, you get the 'need to equip an axe in your hand' warning. So, you have to take your axe and put it in your hand. Which now removes it from the new logging slot. Also, if your shovel was in your hand and you moved that to the terraforming and farming slots ....those also get removed when you put the axe in your hand. So. chopping a tree into logs should be associated with the logging slot as well, to keep things streamlined.