Describes whether a GtkFileChooser is being used to open existing files or to save to a possibly new file.
|Gtk::FILE_CHOOSER_ACTION_OPEN||Indicates open mode. The file chooser will only let the user pick an existing file.|
|Gtk::FILE_CHOOSER_ACTION_SAVE||Indicates save mode. The file chooser will let the user pick an existing file, or type in a new filename.|
|Gtk::FILE_CHOOSER_ACTION_SELECT_FOLDER||Indicates an Open mode for selecting folders. The file chooser will let the user pick an existing folder.|
|Gtk::FILE_CHOOSER_ACTION_CREATE_FOLDER||Indicates a mode for creating a new folder. The file chooser will let the user name an existing or new folder.|