Si no hay ningun problema en hacer algún cambio en la imagen.
Mira te paso un ejemplo:
Código:
<html>
<head>
<script language="javascript">
function fill() {
if (document.form1.f2.value=="") {
document.form1.f2.value = document.form1.f1.value
}
if (document.form1.f3.value=="") {
document.form1.f3.value = document.form1.f1.value
}
}
</script>
</head>
<body>
<form method="post" name="form1">
<input name="f1" onchange="fill();" onFocus="document.getElementById('miImg1').style.border='none'"><img id="miImg1" src="pestanasA.gif" width="10" height="10" onclick="document.form1.f1.value='';document.getElementById('miImg1').style.border='1px solid #000000'"><br>
<input name="f2" onfocus="document.getElementById('miImg2').style.border='none'"><img id="miImg2" src="pestanasA.gif" width="10" height="10" onclick="document.form1.f2.value='';document.getElementById('miImg2').style.border='1px solid #000000'">
<br>
<input name="f3" onfocus="document.getElementById('miImg3').style.border='none'"><img id="miImg3" src="pestanasA.gif" width="10" height="10" onclick="document.form1.f3.value='';document.getElementById('miImg3').style.border='1px solid #000000'">
</form>
</body>
</html>
Saludos!