Ok, so I installed version 4.1.1.0 in another PC, and that entry in the menu is not empty (CTRL- ' ), and it also works toggling from the keyboard. Now the mystery is, how to reconfigure it (I confess I had tried to reassign it), but the option "Toggle Comment" is not present in the shortcut editor. There is an option "Comment Block", which I have added to the enabled keystrokes, but it has no effect. So my question now is, how to reassign it. There is this possibility to export the assignments as an INI file, but with cryptic key codes.