Transaction Rules need a criteria for which bank account the transaction is in.

For example, I have paypal and checking accounts. When I buy something with paypal, I get a new transaction in both accounts. Many times, both transactions (from the banks) have the vendor name in it (Let's say ABC Widgets, Inc.) If I make the rule to catagorized all transactions that have ABC widgets in them as an expense, the problem is, one of the transactions is actually a transfer from my ops to paypal account, not an expense.
Being able to filter by account would say, that the ABC widgets transaction that hits my checking account is a transfer to paypal, and the transaction that hits my paypal is an expense.