Steps to reproduce:
1. Go to the Explorer Demo (http://extjs.com/explorer/#forms) in IE7/Safari.
2. Resize the browser window so that the full form is not on screen and the vertical scroll bar appears to the right of the form.
3. Make sure no field has focus and then click directly onto the button of the DateField marked "Birthday".
4. With the DatePicker displayed on screen, grab the scroll bar to the right and scroll down (or up).

Result: The DatePicker does not close and remains in a static position on the screen as you scroll.

Expected: As it does in Firefox, close the DatePicker when you scroll the form.

Note: If instead of doing step 3 as explained above, you first click into the "Birthday" field (thus giving it focus *before* you pop the DatePicker menu), everything behaves as expected in all browsers.

Offending Browsers: IE7, Safari 3.2.1 (Firefox 3.0.6 behaves as expected)

Thanks!