When we talk about GUI (Graphical User Interface), normally we will develop using our laptop/PC and using popular software like Microsoft Visual Studio, Processing, Eclipse or etc. Since Raspberry Pi is a computer, why not we try to develop GUI on that? And we use Python, the most popular programming language.
This video will show you how to create a simple GUI on Raspberry Pi to control LEDs on Maker pHAT.
This is the sample code to create a simple GUI.