"Preview" button does not obey permalink settings

[philfreo]

Context:
When working on a draft post, there's a "Preview" button that opens a new window to the post URL with "preview=true" in the querystring.

Expected Behavior:
The URL that gets opened would be the same URL that would, when published, be used across the rest of the site, based upon the Permalink settings (but with preview=true in the QS).

Actual Behavior:
The URL that opens up doesn't use the pretty URL based on the settings in Permalinks. Rather it uses the ?p=123 format for the URL. If I manually change the URL to the page-slug (according to my Permalink settings) and add preview=true to the QS then it works - so this should be an easy fix on the edit post page.

[demetris]

I’m not sure about the expected behaviour here. For example, say that you use this permalink structure:

/%postname%

... and you are working on a draft that has no title yet. What would WordPress do then?

[scribu]

A very valid point by demetris.

The Preview button is for previewing the post. For the permalink, you have a sample under the post title field.