Is there some option in Unity 5 to enable visually screen borders which we see only when we build the game?
I am making a 2D game and it will be mostly UI/text stuff so I would like to know where do I place my text fields visually.
I think you’re basically talking about Unity’s “UI” system.
http://docs.unity3d.com/Manual/UISystem.html
Just create a “Canvas” and go from there
Be absolutely sure to use “Scale with screen size” as in the second red arrow.
As you change your device screen size (you actually do that on the GAME view, top left) it will correctly show you that size. You will have to completely learn about the anchor system for placing things relevant to the bottom, top, whatever.
BTW, note that Unity’s UI is sometimes called “new UI” (it is like a couple yrs old now. (Do not, ever, for any reason, use Unity’s “legacy” ui stuff, which is laughably appalling.)