var i1 = new Image();
i1.src = "img/button1_on.gif";
var i2 = new Image();
i2.src = "img/button2_on.gif";
var i3 = new Image();
i3.src = "img/button3_on.gif";
var i4 = new Image();
i4.src = "img/button4_on.gif";
var i5 = new Image();
i5.src = "img/button5_on.gif";
var i6 = new Image();
i6.src = "img/button6_on.gif";
var i7 = new Image();
i7.src = "img/button7_on.gif";

function d(foo) {
	return document.getElementById(foo);
}

function allOut() {
	d('b1').src = "img/button1_off.gif";
	d('b2').src = "img/button2_off.gif";
	d('b3').src = "img/button3_off.gif";
	d('b4').src = "img/button4_off.gif";
	d('b5').src = "img/button5_off.gif";
	d('b6').src = "img/button6_off.gif";
	d('b7').src = "img/button7_off.gif";
}
function over(id) {
	allOut()
	if (id == 'b1') {
		d('b1').src = "img/button1_on.gif";
	} else if (id =='b2') {
		d('b2').src = "img/button2_on.gif";
	} else if (id == 'b3') {
		d('b3').src = "img/button3_on.gif";
	} else if (id == 'b4') {
		d('b4').src = "img/button4_on.gif";
	} else if (id == 'b5') {
		d('b5').src = "img/button5_on.gif";
	} else if (id == 'b6') {
		d('b6').src = "img/button6_on.gif";
	} else if (id == 'b7') {
		d('b7').src = "img/button7_on.gif";
	}
}