The opening

I really liked the opening credits--that stage "Safety Curtain" serving as the background, with those two trumpeters on each side of the woman's face--and then it slowly lifts....and a real, live-action city scene is gradually revealed. One of countless 'Hitchcock' touches.
And as for the phrase 'the opening'...there does seem to be vaginal imagery in "Stage Fright". Dietrich seems to be singing in an underwater womb.