I just posted a Sidemail.io milestone and after clicking the "Save" button nothing happened, so I clicked it again, still nothing... So I clicked it a few more times, and again nothing happened. Ok, this is some kind of a bug I'm thinking, I have to do it all over again. I went to the bathroom, came back and sew the milestone was suddenly posted like 5 times. I kinda freaked out. I immediately deleted the duplicates.
A disabled state for the button while submitting or something similar would be ideal.