A great extension to compensate for a Firefox problem of not syncing or importing favicons. Took a couple of hours to go through about 7k sites. Very well thought out. There is a problem with the folder icon. The folder info from hovering over it is truncated to the size of the sidebar which means you can't tell what the folder is for long folder names. Even stretching the sidebar to its maximum width did not help.

One request I have is to create a log file of the problems, etc. that can be worked later. I had about 1600 problems that I did not have time to go through and fix. Once you leave Checkmarks that session is gone for good.