Asked in Suggestions, but asking here also. Those of you who remember Opera 10 will know what this did. Somehow it disconnects Opera from the web until you toggle it back to Work Online.
I don't know the mechanics of how it worked, but I used it all the time. When selected with a number of tabs open, those tabs are prevented from loading or auto-reloading. This is helpful when opening Opera by eliminating the bandwidth and PC resource load of multiple tabs all loading at once.