Very good bookmark editing capabilities. Rated 5 out of 5 stars

Firefox bookmark manager is poor compared to how opera used to do it. See here: See the left hand side in this screen shot https://drive.google.com/drive/u/1/folders/0B3z9OBGa69jgVVRGQk9SQW1LVFE

I also use "Add bookmark here" which is similar to QuickMark. But QuickMark has MUCH better editing options available when you select Properties (or CTRL-D) of a current bookmark. Good work Martijn!