I have spoken with scientists who have kept many of these creatures, for prolonged periods of time, and have not found any difficulty at all, with any tank smashing.
There is a famous video with Dr Roy Caldwell called "the fastest claw in the west", a BBC documentary with david attenborough which shows a mantis breaking a tank, but only after having been trained AFAIK.
I'd be interested to know what species of mantis broke the glass too.