Mattn was very kind to add this feature immediately. *tips hat* Thank you!
One suggestion for prettifying it a little:
Right now the building preview float shows like this:
Cost:.................................X c
X Days to Build
Running costs:.....................X c
It would look snappier if it was like this:
Days to Build:......................X
Cost:.................................X c
Running costs:.....................X c
Or
Cost:.................................X c
Running costs:.....................X c
Days to Build:......................X
In any case, it is mainly cosmetics. I'm happy to have the feature in the first place, but sooner or later someone is going to bring up the same issue.