jQuery UI对话框模式设置为true不适用于radiobuttons

When the dialog is set to modal it should disable all input elements, but I tried a simple example with a textbox and a radiobutton. When the dialog is opened the text-input is disabled as expected, but i still can check the radiobutton. I used the example from the jQuery-ui demo and a simple html with just a input-textbox and the radio.When the dialog is set to modal it should disab