I know this has been suggested before, but I think it needs to be brought up again. During the last couple of days I've spent 260 gems that I absolutely did not want to spend. 200 gems gone after checking how many gems it cost to finish a book and my computer thinking I was clicking when I was moving the mouse (I play on a laptop) and another 60 after removing troops from the barracks queue and all of a sudden it jumped to the top.
I think it's quite ludicrous that we have a confirmation button for deleting empty wheat fields and wells but none for spending gems. I understand that they want us to spend gems, but on the other hand I'm sure a lot of people feel like me who would never spend real money on the game when there's a risk I might accidentally spend them on something I don't want.
Because of this, I would like to suggest a confirmation button for any gem spending.
Merged