dialog('open') causes form elements to reset on IE7

If you use multiple dialogs on a page, and one has a form with radio buttons, on IE7 the checked radio button will reset to the default when the dialog is opened.

Test case:

test("dialog on IE7 should not reset form elements when opening", function() {
	expect(2);

	d1 = $('<form><input type="radio" name="radio" id="a" value="a" checked="checked"></input>' +
				'<input type="radio" name="radio" id="b" value="b">b</input></form>').dialog({autoOpen: false});

	d1.find('#b')[0].checked = true;
	equal($('input:checked').val(), 'b', "checkbox b is checked");

	d2 = $('<div></div>').dialog({autoOpen: false});

	d1.dialog('open');
	equal($('input:checked').val(), 'b', "checkbox b is checked"); // Fails

	d1.add(d2).remove();
})