virtual void OnInitiateStretch ( [IStretchOperation](API\Editor\SequencerCore\MVVM\Extensions\IStretchOperation) & StretchOperation, [EStretchConstraint](API\Editor\SequencerCore\MVVM\Extensions\UE__Sequencer__EStretchConstrain-) Constraint, [FStretchParameters](API\Editor\SequencerCore\MVVM\Extensions\FStretchParameters) * InOutGlobalParameters )