A designer described the following interface for

A designer described the following interface for a save operation.
The users initially see a screen with a box where they can type the file name (see screen 1). The screen also has 'list' button that they can use to obtain a listing of all the files in the current directory (folder). This list appears in a different window. When the user clicks the 'save' button the system presents a dialogue box to ask the user to confirm the save (see screen 2).

Two programmers independently coded the interface using two different window managers. Programmer A used an event-loop style of program whereas programmer B used a notifier (callback) style.

(a) Sketch out the general structure of each program.
(b) Highlight any potential interface problems you expect from each programmer and how they could attempt to correct them.