Instead of going from left-right, higher-lower priority it would be better (and possibly easier) to have it numbered. For example:
Firefighting is the highest priority, while cleaning is the lowest priority.
Clicking on one of the boxes would raise the priority of the box. For example if you wanted Romero to have Hauling as a higher priority you click on it until it says '2'. The other boxes would lower their priority as needed.
This would stop idle colonists as they would always have something to do after they've completed their (main) task
