Rated 5 out of 5 stars

As an alternative fix for Bug 1293307 - Users should be able to add custom pages to sidebar we now have this add-on. Some first tests with official German SeaMonkey 2.46 FINAL (Windows NT 6.1; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0 Build 20161213183751 (Default Classic Theme) on German WIN7 64bit look very promising.
The add-on is easy to use and works perfect. The only small problem I see: often WINDOWS looses focus to SM in the moment when new Sidebar Panel becomes added.
I will write a more detailed review in the unofficial SeaMonkey blogs within few days after some more testing.

Thanks a lot for this nice tool.