The new Thunder v.188.8.131.52 is already online and it supports Sitefinity 7.0. You can download it from here.
Since, the topic was initially for a Page Selector, for earlier versions, saving the Guid in a custom field and displaying the page url, I attach a simple field control, which has a Page Selector and a textbox which shows the url of the selected page in the current back-end culture in the back-end and resolves the Url to the current front-end Ui culture and shows it as a hyperlink in the front-end view.
I hope you find this useful.
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