There is a big black flicker when clicking on "add page" or "add blog post"

This is related to the fix for Confdev-918

IE7 no longer crashes when I cancel the add page dialog, but the fix appears to have created a black flicker.

From the dashboard:

• click on add page

or

• click on add blog post.

If you keep clicking "add page" or "add blog post" you can see a spinner.