TL;DR
The display panel should have a little speech balloon tail, like the game intro dialogue:What?
If you squint at the textbox when hovering over a display panel, it doesn't have a tail--it is just a floating text box. There are systems for textboxes in Factorio to be a speech balloon pointing from an entity (albeit they are opaque and aligned to one side) as seen in the Freeplay intro and in the Tutorial. Drawing a transparent, centered version of the same triangle 'arrow' on the display panel's window would be a nice detail (the box would probably also have to be raised a few pixels to compensate).Why?
At least in my opinion, the simple rectangle feels like an unfinished UI element.It has been bothering me immensely, and I would greatly appreciate this additional detail.