shift click to "glue" the molecule image to the point
use the option menu (the cogged wheel) to set-up options
use the menu items top left to clean the selection or download the selected rings
you may zoom to a part of the plot by mouse drag
the following shortcut keys are available: 'Esc' (reset all), 'a' (select all visible points), 't' (show tags for all visible points) - the last 2 options are available only for zoomed regions with less then 500 molecules
When you find this tool useful, cite please my paper in J. Chem. Inf. Model.