When you choose “Preview”, which is actually a link,
<a class="preview button" href="?p=52&preview=true"
id="post-preview" tabindex="4">Preview</a>
the post is saved and the preview opens in a new window.
I’m sure there is a javascript event attached to this button, I’d like to override it so that it saves and then preview link opens in the same tab / window.
Here’s a way to do it without modifying the core: