ui.dialog.js doesn't render the dialog correctly

The dialog in http://docs.jquery.com/UI/Dialog doesn't render correctly as shown in "Demo and samples" page(http://dev.jquery.com/view/trunk/plugins/ui/tests/dialog.html). Moreover, the version of ui.dialog.js in "Demo and samples" page is different from the release version of the ui.jquery 1.0.

Moreover, while trying to use buttons options, $(this).dialogClose() will raise a javascript error. The problem occurs because the parameter el is a button instead of the div element of the dialog, which is not expected. However, the code in the "demo and samples" page always works well and the el is always the div element (never become the button such as 'ok' or 'cancel').