CRM 4.0 Quick Campaigns runs activity onLoad javascripts

When creating a quick campaign in Dynamics CRM 4.0 the onload javascripts for appointment, phone call etc. (5 in total) are retrieved and run. In the onLoad scripts for these activity types we hide some fields, however these fields are not actually there when opening the Quick Campaign wizard, and the javascript throws an error.

FormType is 1 (meaning Create), and ObjectTypeCode is the type code for the javascript loaded, so none of these fields give me the context. How can I determine in the onLoad javascripts which setting/context I am in? Are there any global variables that indicate that the context is "Quick Ca开发者_JAVA技巧mpaign Wizard"?

Edit the script and add a truth test before trying to access the properties of the null object

crmForm.all.tab2Tab && crmForm.all.tab2Tab.style.bla='something';