So in a ripple desktop wallet, the wallet keeps 20 xrp's that one cannot spend. Where does that go to? Is it locked up?
Those wallets are quite old, that is the reason of why it is asking you to keep 20 ripple's on your wallet. Just an advice, but if you really want to take care of your ripple's, then the best thing that you can do is just buy a trezor or a ledger nano.