First thing,it is only natural for guys to look at gals.
And if girls do wear skirt,it is her onus to sit properly so that
there is no chance for people to peep.Girls cannot blame guys if
they sit in such manners that their undies are open for the world
to see.
Unless there are guys in the libary who are so daring as to lift up
girls skirt or do other funny stuff,those are different cases
already and those are perverts then who should be punished by the
law.