Bar widgets propagate their composed press-and-hold down to the center gesture
area without handing over the grab, so the gesture area started a bar move and
then received neither a release nor a cancel to end it. The move ghost stayed on
screen for the rest of the session. Ignore the gesture unless we hold the press.
Closes #6881
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
(cherry picked from commit c0a20e2e43)