I did, but with no effect :/ ! I even erased persistent data after changing but it didn't work... Thanks for your time and proposition !
EDIT : I found the problem ! I erased by mistake a # in front of " background Image("gui/textbox.png", xalign=0.5, yalign=1.0)" in the style window !
EDIT OF THE EDIT : I am but a fool and my ancestors are disappointed in me. Changing this # made all my textbox disappear, with or without the phone open. Fixed this, but now the textbox during phone is back.