Io faccio cosi di solito...


this.onRollOver = function() {
color_array = new Array();
for (i=0; i<6; i++) {
color_array[i] = Math.round(Math.random()*16);
if (color_array[i] == "10") {
color_array[i] = "a";
}
if (color_array[i] == "11") {
color_array[i] = "b";
}
if (color_array[i] == "12") {
color_array[i] = "c";
}
if (color_array[i] == "13") {
color_array[i] = "c";
}
if (color_array[i] == "14") {
color_array[i] = "d";
}
if (color_array[i] == "15") {
color_array[i] = "e";
}
if (color_array[i] == "16") {
color_array[i] = "f";
}
}
modif_color = new Color(this);
//Math.round(Math.random()*16)
modif_color.setRGB("0x"+color_array.join(""));
};