You don't have to delete the default number #0, leaving it as it be. Then adding a number you want to send like 2, you will have 02 and click on Send. It's done, without mistake, without need to delete #0 at the starting place.
This is exactly what I used to do always and sometimes when I click on the default number 0 to add just 1 or 2(it's usually what I send of merit). However this time I didn't notice that I added 2 to the left side instead of the right side of 0 and without verifying I clicked on send. Well that was entirely my mistake and I wasn't focused at that time. So whether we received any update on adding another confirmation button or not it's no big deal to me. As you mentioned, Smerits don't matter that much, so it's better to send them to deserving users and useful posts instead of staking them.
Something like this:
Instead of requiring a confirmation button every time you send merits, this option is a better idea. Each user can set the number he want for the notification to prevent accidental sending of large numbers such as 20 or 100 merits for a post that deserves 2 merit and since it cannot be undone I support this idea.
