If you don't want to show a core, or contrib message to the end user, you now have to iterate $_SESSION['messages'] and search for the (translated, token replaced) string to unset it.
If a message has a unique key, you can easily override a message, or unset it.
function backdrop_set_message($message = NULL, $type = 'status', $repeat = TRUE, $message_key = FALSE) {
A simple unset($_SESSION['messages']['status']['unique_key']) could remove the message, and $_SESSION['messages']['status']['unique_key'] = t('Something else'); changes it.
GitHub Issue #:
1062
Recent comments
It could be that you need the Javascript that is included within Seven. If your theme is a subtheme of seven it would be included but if custom, it maybe that you need to copy that and include in...
Nesting problem with field_group 1.x-1.1.1
I was working with a custom admin theme, so there would be nothing you'd need to fix. I just need to look deeper into the css, probably.
Nesting problem with field_group 1.x-1.1.1
Please could you confirm which admin theme it was? Sounds like we might need to get this fixed or removed.
Nesting problem with field_group 1.x-1.1.1