* fix(ui): header, footer and watermark previews step through the pages
The marks dialogs preview the current page, or the first page the range
selects when it leaves the current one out, with no way to look at
another page. Arrows beside the page label step the preview to the
previous or next page the range selects. The page stepped to resets
each time the dialog opens.
* fix(ui): the marks preview forgets a stepped-to page the range leaves out