The problem is that in the "old" programs, it was a generic standard so no specific programming was needed.  In the new GUI world, every field is an object and whatever behavior that object needs to exhibit needs to be explicitly programmed.    
 
We know that F2 as Lookup is a shortcut you are used to and we try to incorporate it.  We are also (in the interest of minimizing the requirement to switch between keyboard and mouse) using Alt-{character} keyboard shortcuts as do many other Windows programs.  For example, Alt-P is Print; Alt-S is Save and Alt-X is Exit.  What used to be up and down arrow between fields is Windows standard Tab and Shift-Tab.
 
For F10, I think you need to try to adjust to Alt-P (Print) or Alt-S (Save) because they are really different functions.

What does GUI stand for?  
I think GUI is another view option as opposed to classic DBA view option .   If that is true when folks say that non-GUI they are referring to the classic view.    
But I believe there is more to it than that because when I scanned the archives it seemed that some tasks worked better in the classic view while others task work better in the GUI view.
 
Thanks
Laura