Recently active topics in Fluid tagged with loop

When quitting a Fluid SSB and a javascript dialog pops up, there is an error. At first the popup is not seen, and then OK and Cancel have no effect. I have to force-quit Fluid.

More specifically, I am using MonkeyGTD as a local file:///Users/foo/gtd.html. Create a new tiddler. Don't save. Quit. In a browser, Javascript says "unsaved changes, click OK to quit anyway or cancel". In Fluid, this popup isn't seen at first, and then OK and Cancel have no effect, the dialog does not go away.