A user of Kerbal Construction Time reported a bug to me today that looks to be caused by MechJeb not clearing the input locks when changing scene out of the editor. When a mechjeb window is behind the KCT launch button, the lock that activates when the cursor is over a mechjeb GUI element does not get cleared, causing the user to be unable to move the camera in flight and persisting after reverting the flight.

A video provided by the user is linked below, clearly showing the issue.
http://youtu.be/x9c5AFSu_CU