After becoming increasingly frustrated with the multi-column-search plugin, I’ve taken the script from my calibre “read next” query and turned it into a tiny plugin of its own. It adds a button to the toolbar which will mark all books with the “readnext” label when clicked, bypassing the need to open up MCS, load an existing query from the difficult-to-read menu, execute the query, and finally close the window again.

The plugin package can be downloaded here.