I currently have a complete CLI program, which consists of around 12 classes. I would like to convert this program into a GUI.

My weak point is using GUI when several classes are involved. My final program is going to have around 5-6 different screens. Should I incorporate the GUI code within each of the 12 classes as appropriate, or will I have to redesign my whole class diagram, or will I have to one class that does all the GUI?

I'm not looking necessarily for the easiest way, but the more "software engineering" way to do this.

Thanks

all you need GUI then write all class using GUI API