connectPreview
Gets emitted when a preview is requested from the native dialog.
The default handler for this signal uses an external viewer application to preview.
To implement a custom print preview, an application must return true from its handler for this signal. In order to use the provided @context for the preview implementation, it must be given a suitable cairo context with method@Gtk.PrintContext.set_cairo_context.
The custom preview implementation can use method@Gtk.PrintOperationPreview.is_selected and method@Gtk.PrintOperationPreview.render_page to find pages which are selected for print and render them. The preview must be finished by calling method@Gtk.PrintOperationPreview.end_preview (typically in response to the user clicking a close button).
Parameters
A combination of ConnectFlags
the Callback to connect. Params: preview the GtkPrintOperationPreview for the current operation; context the GtkPrintContext that will be used; parent the GtkWindow to use as window parent. Returns true if the listener wants to take over control of the preview