I not understand this row "now you take your favorite droplet module and install it as a new module. both variants works in wb 2.8.3 SP4"
we have two modules with the same name and same function -> Droplets
one of them is a part of the wb-core / part of the wb2.8.3 - Package (see Downloads
the other one is a "private" version with a little more functionality (see here
on the first view in AdminTools -> Droplet you see some of the differents (icon to modify, controlbox to activate droplets etc), theses advanced functions are not avaiable in the wb-standard-droplet module
if you upgrade your wb-software, you overwrite some of the files in module/droplet-folder and now you have a mix between advanced droplet module with files from the standard module and because of that you have the error-message with the table-sorter. with this function you can change the displayed order of the droplets via drag&drop, but only in the advanced droplet module.
the file tool.php from the advanced module included the js-file and the backend_body.js use this function, but not in the standard module
both module variants are "correct", both variants works, thats way i write: choose you favorite version. if you like the version from here
, its enough, if you overwrite the files from the server with the files from the zip.
if you go the way over deinstall/new install, see my first post