‘Glimpse' means 'a look at somebody/something for a very short time'. Caught a glimpse is the proper usage.
CTET Solved Paper MCQ - UPTET Feburary 2016
We cannot say discuss about/of. It is wrong. 'Discuss something with somebody' is used.
Stumble means `to hit your foot against something'. 'Stumble over/on something' is the proper use.

