The mashup adds a new "Add Comment" custom unit to the Customise Cards tab in a View Setup area. The unit allows to quickly add a comment to any entity from the list view.
The mashup works really well together with the 'Last Comment Custom Unit' mashup which shows the latest comment to an entity in the list.
You're welcome to install the mashup from Mashups Library.
Once the mashup is installed, please Customize Cards on your list view and insert Add Comment unit to the layout of cards.