In edit mode, pressing "Preview" or "Cancel" button will change the URL shown in location bar to something like:
, and the page being shown is actually using the POST method, which means that if the user *reload* the page the browser would warn that the form data is going to be posted again. This is annoying.
Instead, after canceling or previewing an edit, the user *should* be redirected to the correct page using the GET method. Esp. after canceling an edit, the user should be redirected to the wiki page s/he was viewing, in GET mode, which means: 1) URL in the location bar is correct 2)Reloading the page won't submit the "cancel" request again.
BTW, such redirection is correct, if the user *Saved* the edit.