Indicate new notifications on taskbar icon

Lots of apps indicate new notifications via a red dot in the corner of the taskbar icon,

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Another option is to flash the taskbar icon.

Currently on Windows, notifications show a balloon in the system tray, which is not always apparent (I use dual screens and while gaming and the balloon doesn't show). Various other apps flash the icon in the taskbar.

https://gitlab.com/gitlab-org/gitter/desktop/issues/249#note_76426269

The API for this is FlashWindowEx. I'm not sure if that's helpful for a chrome app but it would be a feature I'd greatly appreciate!

Thanks for your great service!

Duncan