The "File types" container on the left displays all the file types presently known to &xwp;. If you click on any file type, the other two containers will be filled with data (if present).

Initially, this container will display all the WPS file types that have been defined on your system. However, &xwp; adds functionality to that concept in that file types can form a hierarchical tree. This container supports drag and drop within itself so that you can re-arrange your file types to form such a tree. For example, you can drag the "&os2; Command File" type onto the "Plain text" type to make it a subtype (that is, all "&os2; Command Files" will also get the associations for "Plain text").

This container also has &popmenu;s to delete types, create new types, and for "lazy" drag'n'drop ("pickup" and "drop" items).