I have drop down fields with the values 0 - 5, with 0 being the default. I have tried a few validation scripts (below) that work, but only if the value is changed back to '0' so I was wondering if anyone could help me out with a script to display a popup when someone either clicks the drop down and forgets to select a value, or if they tab past the field?

Scripts I've used:

1.

event.rc = true;
if (event.value => "0")
{
    app.alert("You must enter a value other than zero!");
    event.rc = false;
}

if (event.value=="0") app.alert("You must select a value other than zero.");

If there is a script or command to check whether the default value has changed or something along those lines, that wold be great. I appreciate any help.