Zottel: I just checked and yes, it’s caused by exactly what I remembered. You see, each and every add-on has an update address that the browser sniffs periodically (in case of DSWP Bar, this is
http://www.dswp.de/old/dswp_tools/svarox/dswpbar/update.rdf); if it finds the file in the other end reporting that an update is available, by default it downloads and installs it. Now there’s this funny thing that although SvaRoX made his update.rdf point at dswpbar_0_0_3.xpi, he actually hasn’t either uploaded or even finished this version — the update is actually
exactly the same bloody thing! Update installs 0.0.3, which is actually 0.0.2 (and reports its version number accordingly), which prompts the browser to tell you that an update is available, forevermore.
(BTW, warning: DSWP Bar “is not compatible” with Firefox 4 and beyond, that is, it reports too low maxVersion in one of the magic files — when I was doing silly things with it, I also changed this number. Of course, this was before Mozilla went all GNU and decided that integer version numbers are the Right Thing that puts hair on your chest. Hint: maxVersion 9999 sounds good:-P)