This signal is emitted when the preview in a file chooser should be regenerated. For example, this can happen when the currently selected file changes. You should use this signal if you want your file chooser to have a preview widget.

Once you have installed a preview widget with gtk_file_chooser_set_preview_widget(), you should update it when this signal is emitted. You can use the functions gtk_file_chooser_get_preview_filename() or gtk_file_chooser_get_preview_uri() to get the name of the file to preview. Your widget may not be able to preview all kinds of files; your callback must call gtk_file_chooser_set_preview_widget_active() to inform the file chooser about whether the preview was generated successfully or not.

Please see the example code in [Using a Preview Widget][gtkfilechooser-preview].

See also: gtk_file_chooser_set_preview_widget(), gtk_file_chooser_set_preview_widget_active(), gtk_file_chooser_set_use_preview_label(), gtk_file_chooser_get_preview_filename(), gtk_file_chooser_get_preview_uri().

interface FileChooserIF
void delegate dlg
ConnectFlags connectFlags = cast(ConnectFlags)0