[Edit]-[Detail]-[Show space] shows the spaces and tabs in the editor.
+ and - sign in the left of the editing area enables the code to be folded/unfolded but irritates us. To disable this effect, e.g. for C/C++, check off the [Tools]-[Option]-[Text editor]-[C/C++]-[Editing option]-[Outline]. Click [Edit]-[Outline]-[Quit outline].