Gtk.PrintOperation::custom-widget-apply

function callback(print_operation, widget:Gtk.Widget, ):void;

Emitted right before Gtk.PrintOperation::begin-print if you added a custom widget in the Gtk.PrintOperation::create-custom-widget handler. When you get this signal you should read the information from the custom widgets, as the widgets are not guaraneed to be around at a later time.

Since 2.10