SeaMonkey 2.53.1 is the new successor of 2.53, English version works fine for me, German Version caused some problems at the beginning.
…, I call it paranoia.
Until today I was quite happy using zoho.eu for my documents in the cloud.
But today sith SeaMonkey 2.53 I got this “Your browser is not supported, please update to …” crap.
Well, they will stop this, or I will stop using zoho.
As already mentioned in Unofficial SeaMonkey 2.53 by user wg9s and Test Results for Add-Ons from ca-archive, “Go Parent Folder” (and also “Show Parent Folder”) don’t work any longer with latest 2.53 by user wg9s
Go Parent Folder and Show Parent Folder both worked in Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 SeaMonkey/2.53a1 Build 20170731233559. That was a version with the little column selector in the most right table heading in Bookmarks Manager.
The first version still available on my PC where both addons do no longer work is Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 SeaMonkey/2.53 Build 20180902143701. And in this version also the little column selector in the most right table heading has gone. That proves nothing, but might indicate the reason why the addons do no lnger work.
Source and more information: SeaMonkey Project Blog