JavaScript

<script language="JavaScript">
function setVisibility(id1,id2) {
if(document.getElementById('bt1').value=='Show Box 3'){
document.getElementById('bt1').value = 'Show Box 4';
document.getElementById(id1).style.display = 'inline';
document.getElementById(id2).style.display = 'none';
}else{
document.getElementById('bt1').value = 'Show Box 3';
document.getElementById(id1).style.display = 'none';
document.getElementById(id2).style.display = 'inline';
}
}
</script>

HTML

<input type=button name=type id='bt1' value='Show Box 3' onclick="setVisibility('sub3','sub4');";> 
<div id="sub3">Message Box 3</div>
<br><br>
<div id="sub4">Message Box 4</div>