I'm asking 'cause whenever I quickly check in to Gmail and select some messages as spam and then hit close on the window, I get a warning box that some operations are still pending, that limited last-chance page-close dialog JS developers can grasp to. (What's worse, during the time this box is open, apparently no new work gets done in the background (?).) If I close anyway -- because I don't want to stare at my email client doing quiet ajax in the background -- then my messages won't be correctly flagged by my last action. (Or should Gmail memorize my last action in a cookie/ localstorage in case I close quickly?) - Philipp Lenssen