FileChooser.setDoOverwriteConfirmation

Sets whether a file chooser in [gtk.types.FileChooserAction.Save] mode will present a confirmation dialog if the user types a file name that already exists. This is false by default.

If set to true, the chooser will emit the #GtkFileChooser::confirm-overwrite signal when appropriate.

If all you need is the stock confirmation dialog, set this property to true. You can override the way confirmation is done by actually handling the #GtkFileChooser::confirm-overwrite signal; please refer to its documentation for the details.