notifications from firefox's "auto tab discard" plugin never disappear

[kxkv]

the extension "auto tab discard" (https://addons.mozilla.org/en-US/firefox/addon/auto-tab-discard/) sends notification upon for example whitelisting. however, these notification never disappear, despite having set default-timeout in the config file.

~/.config/mako/config:

default-timeout=5000

and yes, firefox is communicating with mako, so it is not this issue. maybe this somehow is related to the same issue that was discovered in #154?