Request: Selectable currency in lm_paypal_donate

Issue Summary

I use the donate module to receive ad-hoc payments in several currencies (normally my customer's currency within Paypal limitations).
Currently my payment "block" has a call to lm_paypal_donate for each currency and, of course, a "pay now" button for each call.
I would like to see teh currency code parameter accept an array of currency codes (similar to array of payment values) which would display a drop down select box of the currency codes in the supplied array.
The parameter would have to be a string or a multi-element array to restrict the user to accepted Paypal currency codes. Using a string (as now) would prevent the user from changing the currency code.

I think this is appropriate only to the donate module (i.e. simplepayment). The subscription and paid_advert modules are more related to a product/service that would be priced in a specific currency.