Tabs widget bugs or change in behaviour between UI 1.7.3 and 1.8.x?

Tabs widget bugs or change in behaviour between UI 1.7.3 and 1.8.x?

Hi everyone

I upgraded an intranet project to jQuery UI 1.8.8 a couple of months back, from 1.7.3
I've since further upgraded it with each new UI release and am currently running 1.8.11

There are a couple of niggles I've noticed that have appeared in UI tabs widget between 1.7.3 and 1.8.1
I've asked about these in the Using jQueryUI forum and on IRC but not got any response to I fear these might be bugs.

I have a test page setup which will illustrate the changes in behaviour I'm alluding to...
http://thenetzone.co.uk/fail/tabs_fail.php
The tabs are at the base of the page and there are links at the top to switch between jQuery UI versions.

1) With UI 1.8.x I see a strange double-load effect when loading tab content through AJAX.
If you switch between tabs you'll see the random and timestamp quickly change values before displaying the final value which suggests there's some sort of double-load or caching going on.
However Firebug only reports a single AJAX request being fired.
If you switch to jQueryUI 1.7.3 you'll notice the double-load effect no longer happens!
It's almost as if with 1.8.x it's loading the previous AJAX content on tab change then replacing it once the new AJAX content has been received.
The PHP code used to generate the tab content in the test is set to send the following headers to prevent caching of the tab content...
  1. header('Expires: Sat, 26 Jul 1997 05:00:00 GMT');
    header('Cache-Control: no-store, no-cache, must-revalidate');
    header('Pragma: no-cache');


2) When switching to a new tab for the first time, the user's viewport is scrolled up to a baseline underneath the tab bar. However on subsequent tab loads, the viewport doesn't scroll. It's only on loading a new tab for the first time that the re-scroll occurs. This isn't the case with jQueryUI 1.7.3

Is anyone able to reproduce these issues or know what's going on?
Are these bugs, or are they known changes in behaviour?

Cheers, B