GtkFileSelection is used to retrieve files or
directories requested by the end user. The widget contains a directory
list and a file list which will correspond to the default directory,
that is, either the current working directory or one determined using
set_filename() .
The filesystem can be navigated using either the directory tree or
the dropdown history menu. Alternatively it is possible to type the
directory or file path into the
selection_entry field,
and also to use the TAB key to autocomplete either
the directory name or file name entered in this way.