Ho risolto! E' sufficiente inserire questo codice nel primo frame del .swf che si carica (supponendo che il nome istanza del button sia "foto ")


// On page load /initialize
function onInit() {
// Save current autoFlip value in order to restore it later
autoFlip = book.autoFlipProp;
// If page is not visible for user
if (!visible) {
disableButtons();
}
}
// User has moved to some other page
function onClose() {
disableButtons();
}
// User has moved to this page
function onOpen() {
enableButtons();
}
function turnFlipOff() {
book.autoFlipProp = 0;
book.flipOnClickProp = false;
}
function turnFlipOn() {
book.autoFlipProp = autoFlip;
book.flipOnClickProp = true;
}
function enableButtons() {
foto. enabled = true;
}
function disableButtons() {
foto .enabled = false;
}