jit.cornerpin corners wont stay put when adjusting another

Making a basic projection mapping app, everything is working great other than the fact that either the entire texture won't be applied (using position .5 on Z-axis) or if that's 0, whenever I adjust one corner, all the others move...

EDIT: I messed around a little bit, and it appears with corner icons enabled the corners themselves aren't moving. The problem is that the texture doesn't automatically stretch to fit, is there a way to force this?