Hi all!
I had a client call in to ask why the CustomerType drop down (in the CustomerList->Additional Info tab) included items that were inactive in Quickbooks. She also mentioned that she couldn't find an answer on our forums - so here I am :)
This can also apply to dropdowns on other Method screens. What you need to do is - you got it - customize!
1) In Customize->Screens, copy the original screen (in this case Customer List). Now Edit your copy.
2) find the "type" field in your screen layout. Edit it.
3) in the last step of the wizard (step 5 of 5), this is where you insert a filter for the "isActive" field. You'll want to filter for records where isActive is equal to yes.
4) Publish!
Hope that helps :)