Select wall row and upgrade them in all one go.
I think it would be a great idea to be able to upgrade a selected row of walls and upgrade them in all one go. It would make it much easier as it is hard to click each and every wall and upgrade them each at one time. It would give you an option to upgrade the selected walls in one go next to the rotate button. When you click the Upgrade button it will ask you if you are sure you want to upgrade the selected portion. I hope you could add this to the game as i think most of the community would enjoy this useful feature.
If you have any ideas or revisions please post your ideas below.