Was re-working on my screen 1,1 (the one displayed just after my intro/cutscenes...)
I save, I compile & test... ARG... it's not ok.
Come back to my screen 1,1, I use right arrow key to go to screen 2,1.. then left arrow key to come back to 1,1.
My screen is back to the previous "state" :S
The video in action: https://youtu.be/C_QIIyGjaS8