protuberances 28 are coaxially aligned with the holes 24 of the component 14 unlike in fig6 however these protuberances 28 are independently moveable such that only those not in contact with an obstruction 16 are able to protrude from the surface of the edge 14 a in a preferred embodiment not shown the protuberances 28 are in a normally recessed position relative to the surface of the edge 14 a so as to produce a smooth surface here a plurality of actuators 30 again preferably comprising active material elements 18 are drivenly coupled to the protuberances 28 and are operable to cause the protuberances 28 to extend from the edge 14 a either individually or as a unit when closure of the panel 12 is initiated the protuberances 28 are then automatically locked in the extended position it is appreciated in this configuration that the mechanism 10 serves to both generate a haptic warning caused by the actuation pressure exerted upon the depressed protuberances 28 and a mitigating cavity where the obstruction 16 persists alternatively and as shown in fig7 the protuberances 28 may be biased towards the extended condition by a plurality of springs 32 and more preferably shape memory alloy springs so as to enable attenuation in this configuration the mechanism 10 includes a locking mechanism i e u201c lock u201d 34 operable to selectively engage and retain the non engaged protuberances 28 in the extended condition fig7 for example a plurality of individual sliders 36 may be selectively shiftable between clear and supporting.