User Interface
Open up the Content drawer, create a new widget blueprint and name it "WBP_HUD".
If you have an existing HUD display in your project, you should use that one instead of creating a new one. Having multiple widgets on screen can reduce performance.
Place the WBP_NotificationPanel inside the HUD and anchor it to any position you want.
On the WBP_NotificationPanel, set the option Size To Content to true, this will make sure the panel resizes itself based on the notifications inside it.
By default, the notifications go top to bottom, but you can change the order by changing the Y allignment of the panel to 1, this will make the notifications go from bottom to top.
Inside your player controller, on begin play, create the HUD and add it to the viewport.