After upgrading to Texstudio 2.9.4, I noticed that the Backspace, delete and return entries of the keyboard were no longer functional in edition mode. The problem was solved when I downgraded to 2.9.0. I tried to re-install the 2.9.4 version from scratch and encountered the same issue. Has someone else already encountered this problem ?
please follow procedure as described here.
http://sourceforge.net/p/texstudio/bugs/1264/
(delete lines in texstudio.ini)