I use the Tags feature as the main way to organise my library. Unfortunately Tags are only accessible in the details pane in the library view.
I usually add tags whilst I am reading a paper, but as tags aren't available in the Reader view I have to keep switching back and forth between Library and Reader. Much nicer would be to have the tagging functionality accessed in the left-hand Menu pane, alongside Notes, when in Reader view.
Agreed, this would also be very nice to have for my workflow.
The whole implementation of tags could be improved, from editing to viewing and sorting. Tags was perhaps one of the strongest aspects of Mendeley (however this feature has not yet been implemented in their latest 'Mendeley Reference Manager' software - a reason I am looking for alternative software)