I use Mozilla's Thunderbird for email on Mac OS X and like it very much. In addition I use Thunderbird's add-on calendar called Lightning, also very satisfactory. Recently I have set up a Google Calendar and have coupled my Lightning Calendar to my Google Calendar. The question that I have, which is detailed in the four attached screenshots, is this: Is there a way to toggle the "Calendar" field in all of the events of a Lightning Calendar rather than doing so one-by-one? Alternatively if there is no way, is there perhaps a file in the Thunderbird folder (on Mac OS stored here : /Users/andynic/Library/Thunderbird ) that I could edit with the Wrangler editor or over which I could run a perl script that could make the required changes? Thanks for your help. Andynic