What is the easiest or smartest way to create a popup notification from a browser? I am trying to code a browser chat application and I need the application to be able to reliably notify the user when a message arrives. This notification has to be as visible (and audible?) as a Skype incoming message would be. It doesn't matter how exactly the notification is shown, but it should be VISIBLE. Meaning taskbar flashing, traytip flashing, small window in the corner on TOP layer of desktop... Anything as long as it's always (or almost always) notable even the browser is minimized. And this has to work on both OSX and Windows.
This chat application should work on OSX/Windows but can be browser-dependent if necessary (can work only in Firefox for example). Also it's best if no plugins are necessary, but plugins is also a possibility if that's the smartest way to go.