Thanks for the hints!
Now I understand why this bookmark feature was missed by so many people.
the bookmark jumps are missing in the edit menu but they are in the code context menu so easy to look up if I forget about the right key combo.
I don't know if I should log this as a bug but this doesn't work right...
right click line > toggle bookmark
right click another line > toggle bookmark
first bookmark is removed instead of creating a second one because the line is not really selected yet.