I have added a new pull request to the sprouts github that removes the checkpoint warning in the wallet.  It can be found here: https://github.com/sproutcoin/sprouts/pull/6

Since it will probably not be merged because the repository seems to not be maintained anymore, you can get the source with the merged request included from my sprouts fork at: https://github.com/ctgiant/sprouts

Bounty address is the same as the post above.