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
The custom preview implementation can use is_selected and render_page to find pages which are selected for print and render them. The preview must be finished by calling end_preview (typically in response to the user clicking a close button).
the PrintOperationPreview for the current operation
the PrintContext that will be used
the Window to use as window parent, or null
true if the listener wants to take over control of the preview