CefWindowInfoWindowlessRenderingEnabled Property

Set to true (1) to create the browser using windowless (off-screen) rendering. No window will be created for the browser and all rendering will occur via the CefRenderHandler interface. The |parent_window| value will be used to identify monitor info and to act as the parent window for dialogs, context menus, etc. If |parent_window| is not provided then the main screen monitor will be used and some functionality that requires a parent window may not function correctly. In order to create windowless browsers the CefSettings.windowless_rendering_enabled value must be set to true.

public abstract bool WindowlessRenderingEnabled { get; set; }