Showing/Hiding tabs based on the selection in a picklist

The next script shows one out of three tabs based on the selection in the new_combo field. It hides all tabs if no selection is made or a different value is selected. OnLoad:

// Jscript
//Sanity check: if new_combo is not present on the form, then don't call FireOnChange
if (crmForm.all.new_combo != null) {
crmForm.all.new_combo.FireOnChange();
}