Steps to reproduce:
Go to Bookmarks Manager (Ctrl+Shift+O). Select a few bookmarks (i.e., 5), right click and select "Open in new window".
Now, each successive bookmark opens as a child of the previous.
The first bookmark to open should be made the parent of all the other bookmarks to follow. However, it should only have children 1 level deep instead of n-levels.
Not exactly a bug, but not a feature either... I hope! ;)
Customer support service by UserEcho