Notebook is a new note taking tool from Mendeley Reference Manager. Notebook allows you to highlight PDFs attached to your references, keep your notes from multiple PDFs in the same place, and retains links back to the source PDF.
You can highlight passages and attach notes to any .pdf attached to a Mendeley reference.
Highlighting
Inserting Notes
You can create individual Notebook pages to collect highlights and notes from several attachments. This is really useful to help organize passages from across several sources.