Removed the OnFindBurnable check to reduce lag (however, the UI will now only refresh when you close/open the furnace UI or when the furnace is sorted).
I've reverted the plugin to using the CanAcceptItem hook instead of CanMoveItem. This should fix the issues with StacksExtended and any duping issues you were experiencing. Sorry for any inconvenience!
- Sorting whilst the furnace is burning is now allowed
- The UI now shows the time remaining on the furnace to finish smelting
- On the UI there is now an option for the number of stacks of a specific item you want to split between