@printoperation: the object which received the signal.
+<!-- ##### SIGNAL GtkPrintOperation::update-custom-widget ##### -->
+<para>
+
+</para>
+
+@printoperation: the object which received the signal.
+@widget:
+@arg1:
+@arg2:
+
<!-- ##### ARG GtkPrintOperation:allow-async ##### -->
<para>