Hello Solen,
Using ABAP screens you cannot achieve 100% MVC. So you have to use workarounds like creating the screen in a FuGr, Global program & then calling it. If you do so, then all the standard behaviour of the screens may not be available.
But one issue when you execute the report and press GO BACK standard button it doesnot come back to your selection screen but way to your code.
Yes, because it returns to the calling position which is the code in your case. For e.g., if you create a transaction for this report & then it'll return to the main/SAP menu. This is a known problem 
The trick here is to put the CALL SELECTION-SCREEN statement in an endless loop e.g., DO...ENDDO.
I don't quite like the idea of introducing the infinite loop in your code. So i visualize the report to be my view - displaying the screen, ALV etc. - and program accordingly.
A few interesting blog(s) you can refer to are -
- Get over ABAP Reports, create object-oriented Selection Screens
- Global Data in ABAP OO Programs
- Read Matthew's comment on how to trigger WD apps from your program - Classical way to ABAP OO style of coding
BR,
Suhas