The Lister

Listers are what you might call the Opus "main window" - in a traditional file manager, they would be the main (or only) window. The name Lister derives from the original Opus on the Amiga computer (20 years ago!). Listers were much simpler then, doing nothing much more than displaying a list of files and folders - and what do you call something that lists things? A lister!

These days the Opus Lister contains multiple configurable user-interface elements that let you access various program functionality. At their core though they still display lists of files and folders, and indeed this is the only functionality of a Lister that can't be disabled.
 

Above is a screenshot of a fairly simple Lister using the default Opus configuration. The two default toolbars are visible at the top of the Lister, then below this are the folder tree (on the left), and the file display on the right. The file display has a third toolbar at the top of it. The folder tree indicates that drive C: has been selected and indeed, you can see that the contents of drive C: are shown in the file display to the right of the tree. Note the folder tab displayed at the bottom of the file display - currently, only one tab is open (the one showing C:) but you can open as many folders as you like each in their own tab, and rapidly switch between them.

At the  bottom of the file display is the status bar, which displays some summary information about the folder shown in the file display. The information displayed on the status bar can be configured through the Preferences system.

You might think from that image that a Lister is basically the same as Explorer - in which case, what's the point of Opus? In fact, Opus has been deliberately designed to resemble Explorer in its default configuration. This provides a sense of familiarity for new users first switching from Explorer - if you've used Explorer before you can instantly start using Opus in the same way, and learn more about its additional functionality and configurability as you go.

This screenshot illustrates a much more complex Lister, and immediately you can see that the resemblance to Explorer is only superficial. The key user interface elements visible in this screenshot are:

• File Displays: The core element of the Lister, the file display lets you see the contents of the current folder. You can choose how files and folders are arranged (both sorting and grouping can be configured), and you can use filters to hide or show certain files or types of files. Most actions (like copying / deleting files, creating folders, adding to archives, etc) take place within the file displays. Listers can display either one or two file displays simultaneously, and each file display can have one or more tabs, each of which can display the contents of a different folder. Each file display has a configurable toolbar displayed above it that shows the current location and provides basic navigation buttons. There are a number of options in Preferences that affect the appearance and behaviour of file displays (for example, you can have grid lines shown, enable full-row selection mode, etc). See the File Displays and File Display Modes categories in Preferences for more information.
• Default Toolbars: The Menu and Operations toolbars are the default set of toolbars built-in to Opus. These toolbars can be turned on or off, and edited, but they can't be deleted or renamed - and you can easily reset them to their defaults at any time. Also shown above is the default Images toolbar, which is displayed whenever a file display is set to thumbnails mode. Of course you can create your own toolbars with any combination of buttons that you like - many people turn off the default toolbars as soon as they install Opus and never look at them again!
• Folder Trees: The folder tree displays the folder hierarchy that leads to the currently selected folder. You can turn the folder trees on or off, and in a dual display Lister, you can choose to have a separate folder tree for each file display, or a single folder tree that is shared between them. Folder Trees can be both a navigational tool (clicking on a new folder in the tree will display its contents in the file display), and as a target for file operations (e.g. you can drag a file from the file display and drop it on another folder in the tree to copy or move it).
• Viewer Pane: The Viewer pane displays the contents of the selected file. Opus supports dozens of different image and movie file formats natively, and also has a viewer plugin system that lets third-party developers write viewers for unsupported file types. Additionally, Opus ships with a viewer plugin that leverages ActiveX technology to display files like Office and PDF documents.
• Utility Panel: This is a multi-facted panel that provides access to several utility features, including Find (search for files and folders, based on definable criteria), Synchronize (synchronize the contents of one drive or folder, including remote FTP sites, with another) and Duplicate Files (search for any files that are duplicated, or for duplicates of specific files). Additionally, the Utility Panel is used to display several logs including the file operations log, the FTP activity log and script output.
• Metadata Pane: This pane lets you view and edit the metadata for the selected file or files. Many different image, music and document file types are supported.
• Status Bar: Displays statistics on the current folder, including total number of files, files hidden by filters, free space on the drive and more. You can configure what information is displayed through Preferences.
• Filter Bar: Provides quick access to filename filters, letting you control which files are shown or hidden in the folder.
• Folder Tabs: Using Folder Tabs you can open multiple folders at the same time and easily switch between them.