Here you go, try this. I didn't test it very much, but it seemed to work fine. If you run into any problems let me know & I'll fix it.
LibNotifications
And P.S. there is also ZO_Alert() to display alert messages in the upper right hand corner:
Lua Code:
ZO_Alert(UI_ALERT_CATEGORY_ERROR, SOUNDS.NEGATIVE_CLICK, "some message")