This dialog box lets you configure the tabs in the Contents Window. You can reorder the settings and/or hide individual tabs which are of no interest to you.
"CRiSP is the only UNIX text editor I've seen that would allow a DOS/Windows
user to be immediately productive. But it also has a seemingly
unlimited list of power-user features. I like it so much at work that I
bought it to use at home (under Linux)."