Currently, there does not seem to be any sort of direct shortcut to add an annotated bookmark to code in the editor. There is a mouse (shift click margin) and keyboard (ctrl M) shortcut for creating a bookmark with no annotation, but then, according to the manual:

I'd find it extremely useful if there was a keyboard shortcut that immediately prompted for the annotation, so that the flow was:

1. Press keyboard shortcut on the line you want to bookmark. Annotation dialog pops up with focus already on input field.
2. Type the annotation and press enter (or esc to cancel). Dialog closes, bookmark is created (unless cancelled, of course).

Also - and this is just icing on the cake - I would find it useful if existing annotations on bookmarks could be edited by clicking the blue annotation text displayed after the code in the editor (either click -> dialog, or click -> edit inline, I have no preference there).

Thanks!