ie 에서는 radio 버튼 동작을 방향키로 제어 가능하다.
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On IE, when a radio button group is reached via tabbing, the initially selected button is focused on, and the dotted rectangle indicates this. You can use arrow keys to move between the buttons inside the group; both "down" and "right" arrow move forward inside the group, and both "up" and "left" arrow move backward. And upon moving to a button, that button gets checked (and the button in the group that was checked gets unchecked).
http://stackoverflow.com/questions/10739863/radio-button-keyboard-trap
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