Markshas Marks visibility button in Paragraph Ribbon Group.
How it can be set by code?

HI Junghyron,

You can turn off the visibility of all formatting marks using:

nRichTextViewWithRibbonControl.View.ViewSettings.MarksVisiblity = ENMarkVisibility.None;

The ViewSettings object also has properties to control the visibility of individual mark types like paragraph, line break, section break etc. Let us know if you have any questions.

Best Regards,
Nevron Support Team