I personally hate having to select one wall at a time to upgrade them so i thought of well many thought of this.
upgrade the entire row you select instead.
Here a picture of the idea.
as you click on this photo to enlarge it you'll notice the upgrade button next to the turn button.
with this we can add up the cost of each wall and upgrade them at the same time.
Attachment 24319
Took me awhile to edited though. to include the upgrade button i had to get a pic of a million coin because the maximum cost of these walls are a million together and merge the pic over the price of one wall and the merge it next to the turn button.
This was my first edited photo.
And SC might see this a lot more clearly rather than many post about it in words.

