synergy1, The widow makers in my area us old timers were referring to are old GE & FPE panels. These panels had a screw through the cover you loosened. You then rotated the washer behind the screw a quarter turn. This released the clamp inside that held the cover on. They worked well on a new panel with not many conductors in the gutter space. Over time they work lousy and grab the energized conductors in the gutter space. If you were lucky the breaker tripped when the conductor got pinched by the clamp. FPE
& old GE breakers do not like to trip. Thus the name "Widow Makers".
Al
