Client drop down list for billing

A recent (unannounced) change to the drop down list for clients in the billing area now includes all clients who have approved shifts that have not yet been billed. Great idea! However, the drop down client list includes clients who have approved shifts that are marked as Not Billable. Clients who have Approved shifts that are billable (and not yet billed) should be on the client list. Clients who have Approved shifts that have already been billed should not be on the drop down client list. Not Billable shifts should not cause a client name to be on the drop down client list. There is no way to remove a client's name from the drop down client list when the only reason the client name is there is due to Not Billable shfts. Over time, the client list will just continue to grow & be less user friendly. (Our drop down list has grown from ~40 to over 90 due to this change.)