Vote timer and vote captcha.
Hi! I voted negatively someone by mistake (im using a phone) and i seen it is not possible to un-do it. I think that maybe a timer that for let's say the first 30 seconds since the vote lets you change/cancel it would help in such cases.
Also a captcha would vastly help against people that uses bots for voting.
captcha requires centralized validation, bots don't use the web interface, they broadcast on the blockchain directly.
You should have the ability to change votes soon.
Thanks for your fast reply.