The user interface should be self-explanatory, but some bloggers have complained about under-documentation of the user interfaces of software, so here I go.
This information refers to R3R 2.0 Beta 1+ wxWidgets GUI. The 1.2.x GUI was quite similar, though.
The main window is nothing out of the ordinary. There's a menu bar, the feed list below that, the area for the textual description below that, and the status bar (for errors, network message, etc) below that.
The menu bar has the conventional, if badly named, File and Help menus, as well as the Tools menu.
Below is a description of the menu items.
The feed list is a list of feeds. It consists of four columns: the feed name, the item title, the subject, and the creation date. If any of these weren't specified, [None] will be displayed in its place.
The first used column will be the feed name for the first item of a feed, and the item title for the following items. Subjects are assigned by the feed authors and can be anything. In the future, it may be possible to filter certain subjects.
The creation date is currently author-assigned. Some feed formats use the standard long date format, but others use the standard short date format. The exception is ESF feeds, which uses UNIX timestamps; in this situation, R3R will convert it to the standard short date format.
You can navigate through the items with the arrow keys, or by scrolling. Items can be selected by left-clicking or pressing the enter key. The web address of the item's web representation is in the status bar. The address can be visited by pressing the enter key on a selected item or by double-clicking an unselected item (if the item is selected, you must unselect it first).
To unselect the item, you do the same procedure you used to select it.
The feed description box is a scrolled widget that contains the textual description that can be scrolled.
The full title is displayed in the box label.
The status bar contains the web address of the current item.
The settings window allows you to change various configurable aspects of the program. Currently, nothing configurable is located outside of this window.
The treebook contains several items, with each item having one or more settings.
These are the Accept and Accept-Languages headers that are sent. The former should not be changed, as it's the formats R3R can understand, in the preferred order; however, rearranging them by preference should be OK. The latter is the languages that you speak, with an optional quality factor (from 0.0, never to 1.0, always); the default is blank (any language).
The programs used for visiting web resources, sending e-mail and viewing feed sources, respectively.
Contains your user agent, in the format: R3R/version (operating-system operating-system-version) other-used-components.