void gtk_file_chooser_add_filter ( GtkFileChooser* chooser, GtkFileFilter* filter )
filter to the list of filters that the user can select between.
When a filter is selected, only files that are passed by that
filter are displayed.
Note that the
chooser takes ownership of the filter, so you have to
ref and sink it if you want to keep a reference.
Available since: 2.4
The instance takes ownership of the data, and is responsible for freeing it.