>Neither of them works on Windows 7 x64 (SP 1). The first two work on Linux (Fedora 20 x64). Neither of the non-working ones generates any error/warning.
Ideally the alerts service would work on all platforms, so I don't know
why you're having a problem on Windows (but I haven't tried it myself)
>Please, suggest how/where to do that, or how to 'schedule it' (as an event handler to a system event, I suppose) from my overlay of browser.xul.
You could try adding a observer service notification for
sessionstore-windows-restored which will then give you a chance to find
a browser window and post a notification to its notificationbox.