Here is my code.
Edit: fixed the code up a bit
What this does is make my own folder called Extension Folder under the Bookmarks Menu folder, then tries to add a bookmark into that folder by specifying the folders id as the parentId of the new bookmark. Despite this, the bookmark always ends up in the Other Bookmarks folder instead of my folder, though my folder itself does get created. The parentId of the new bookmark even gets set correctly according to the debugger. Any help?