GM.notification
From GreaseSpot Wiki
Description
This method opens the specified URL in a new tab.
Syntax
function GM.notification( text, title, image, onclick )
Compatibility: Greasemonkey 4.0+
Arguments
text
String
The main notification text.title
String
The title of the notification.image
String
Optional: The URL for an image to display in the dialog. If not provided, the Greasemonkey logo by default.onclick
Function
Optional: callback, triggered when the notification's button is clicked.
Returns
undefined
Examples
GM.notification("A new widget is available at the frobber.", "New widget!");
The appearance is platform specific, but could be for example: