On the Amiga, accessing the pulldown menus caused the display to be temporarily frozen, so that the menu panel could be rendered off screen and then swapped in using the blitter and the XOR trick. It wasn’t as fast as a straight copy, but it saved on precious memory, and it rendered very cleanly.
When you released to the menu button on the mouse, it did a similar swap to restore the screen contents. In version 2.0 I optimized it to do a simple copy of the offscreen rectangle back onto the screen because before it was wasting time in order to preserve the menu pixels that we’re going to be thrown away immediately.
Hedley Davis, much loved hardware engineer who worked at Commodore (A1351 mouse, Amiga 3000, A2024 "Hedley Hires" monitor), 3DO, Microsoft (Xbox, Xbox 360) passed away on March 9th. If you didn't know him, here's a three minute look into what made him such a delight: https://www.youtube.com/watch?v=AolGGPqcU-w
I believe cosmologists generally refer to the Big Bang theory as the progression from the hot dense state to the modern shape. This Hot Big Bang part is very well understood in theory and very well supported in observation, with the Cosmic Microwave Background being a pre-eminent discovery supporting that.
What preceded the hot dense soup involves conditions that are a problem for both theory and experiment. For theory, those conditions involve both quantum gravity and general relativity and we don't have any accepted way to resolve those yet. And, for experiment, the hot dense soup is opaque to our observations. There are educated guesses as to what might have come before, and one guess is that it leads back to a singularity, and the popular view of the Big Bang theory is often that singularity as the kickoff, but we don't have anything resembling evidence. And whether anything came "before" even that is super speculation, even the concept of "before" may not apply.
“There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.
There is another theory which states that this has already happened.”
-- Douglas Adams
When you released to the menu button on the mouse, it did a similar swap to restore the screen contents. In version 2.0 I optimized it to do a simple copy of the offscreen rectangle back onto the screen because before it was wasting time in order to preserve the menu pixels that we’re going to be thrown away immediately.