Does scriptPreferences.userInteractionLevel what it should do?

Using ID CS3 (5.0.3 @ Windows, german version) I have the following question:

The object model tells me that - with JavaScript -
app.scriptingLevel.userInteractionLevel controls the display of alerts and dialogs. The simplest script to check this "promise" is the following:

app.scriptPreferences.userInteractionLevel = UserInteractionLevels.INTERACT_WITH_ALL;

alert("I expect this message because interactionLevel is " + app.scriptPreferences.userInteractionLevel);



app.scriptPreferences.userInteractionLevel = UserInteractionLevels.NEVER_INTERACT;

alert("I don't expect this message because  interactionLevel is " + app.scriptPreferences.userInteractionLevel);

What's happening is that both alert boxes are shown - the userInteractionLevel does not prevent the second one from to be shown. This is in contrast to the docs and everything I read in the forum.

This switch obviously seems to be useless. Or do I miss something? Does this switch only affect "internal" alerts? Which ones?

Any help or additional ideas will be appreciated!

Thanks.