Thunar

Thunar is a file manager for Linux and other Unix-like systems, initially written using the GTK+ 2 toolkit and later ported to the GTK+ 3 toolkit. It started to ship with Xfce in version 4.4 RC1 and later. Thunar is developed by Benedikt Meurer, and was originally intended to replace XFFM, Xfce's previous file manager. It was initially called Filer but was changed to Thunar due to a name clash.

Thunar is designed to start up faster and be more responsive than some other Linux file managers, such as GNOME Files and Konqueror. Accessibility is accomplished using GNOME Accessibility Toolkit. Like the rest of Xfce, Thunar is designed to comply with standards, such as those stated at freedesktop.org. Thunar is simple and lightweight by design, but its functionality can be extended through plugins.

Thunar is the Old Saxon name of Thor, the god of thunder in Norse mythology, and uses Mjölnir, Thor's hammer, as its icon.

Interface
The Thunar interface was developed prior to the coding of its core. A minimally functional software mockup was built in Python. Features were added and UI elements changed iteratively to react to test user input.

API
Thunar provides an API for third-party developers: Thunar can also be extended by writing scripts to be placed in the context menu for various file types.
 * The "thunar-vfs" is a cross-platform API for high-level file system operations. This is deprecated for the 1.2.0 release in favor of the native GVfs.
 * The "thunarx" is a library for building extensions to the file manager itself.
 * Lacking is an API to resolve folder symbolic links properly to "open the parent folder", not the symbolic link's folder.