I suggested this before but it was at the end of a thread so I'm not sure anyone even read it.
Currently the building screens show the enabled Upgrade button if the building can be upgraded and the disabled Upgrade button when there are no more upgrades.
This is kinda annoying because you need to check separately if you have enough money to upgrade. And if there are no more possible upgrades, why is the button even there anymore?
Show the enabled button if there's an upgrade and you have enough money.
Show the disabled button if there's an upgrade and you don't have enough money yet.
Remove the button altogether if there are no more possible upgrades.
Even better would be if you could also see which buildings you can still upgrade directly in the main screen (e.g. building marked by a * symbol or something).
This is not a big issue but the disabled upgrade button just keeps bugging me as I keep thinking maybe there's still one more upgrade to this building and I just haven't found how to unlock it...