|GTK+ Reference Manual|
GtkFileChooser is an abstract interface that can be implemented by widgets that perform file selection tasks. Two widgets in GTK+ implement this interface: GtkFileChooserDialog and GtkFileChooserWidget. Most applications simply need to use GtkFileChooserDialog, which is a dialog box that allows the user to select existing files for opening them, or to pick new filenames for saving documents. GtkFileChooserWidget is for special applications that need to embed a file selection widget inside a larger window. In the context of GTK+, GtkFileChooserDialog is simply a GtkDialog box with a GtkFileChooserWidget. inside.
To create a GtkFileChooserDialog, you simply call gtk_file_chooser_dialog_new(). This function is similar to gtk_dialog_new() in that it takes parameters for the title of the dialog box and its transient parent, as well as its buttons. In addition, it takes in an argument that determines whether the file chooser dialog will be used for opening existing files or for saving to a possibly new file.
Please see Example 7, “Typical usage” for how to create a simple file chooser dialog and extract the selected filename from it.