As others have said, this is an annoyance. It's true that when we stop debugging, we can go to project properties and disable reloading. Then after making code changes, we can go back to project properties and enable reloading, if we think of it.
Awneil suggested another entry on the debug menu. "Start debugging without reloading". That is better than what we have now.
But isn't there a better way? Couldn't the debugger check to see if the code has changed, and not reload if the code has not changed?
As I recall, AS4 did that, but maybe I'm just dreaming.