Renders a page to the preview.
This is using the print context that was passed to the [[email protected]:GtkPrintOperationPreview:preview] handler
together with this.
A custom print preview should use this function to render the currently selected page.
Note that this function requires a suitable cairo context to be associated with the print context.
| this |
a `GtkPrintOperationPreview` |
| page_nr |
the page to render |