Actually, despite what Padfoot says, I for one am certainly here to further my understanding of the Laws, rather than find ways to re-interpret them.
And listening to everyone's discussion has really sorted it out for me. I would now say that I am coming down 100 per cent on the side of those who say the slightest touch of the keeper's hand or arm (just one will do) constitutes control. It is clearly impossible to give any other reading to it. And to those who say that control cannot be defined like that, I say I agree with those who say control can (as a specific football technical term) mean whatever the Lawmakers chose it to mean.
This appears to be the thing causing several of us a problem. And the Laws unequivocally say YES, a slight touch gives control and NO, the keeper cannot be challenged. But if the ball on the ground merely flicks the goalie's fingers and runs free again, the Law makes it clear that as either an accidental rebound or a save, there was in fact no control, and anyway the attacker can now play for the ball (as can the keeper again).. If that slight touch halts the ball enough for the keeper to fully touch it and pick it up...well, good for them. Also the punch in the air, is a clear save and a millisecond later the ball is playable again.
For me, truly simultaneous touches would be rare anyway...one player or other will arrive earlier, even if only half a second. We are taught at referee meetings here to beware of calling "simultaneous" for double fouls (which would have to be a drop ball) and pick a direction to give the free kick. This is a variant case: either pick the keeper as arriving early (free kick) or the striker playing ball first (play on).
As pointed out right at the beginning of this thread (and this was also confusing me) this is really all that needed to be said. All the stuff about ball between hand and ground or on outstretched palm is really covered by the simple touching Law. But what is clearly happening is the Laws are giving us a few examples to clarify EXACTLY what is and is not allowed.
Congratulations gentlemen, your probing and intelligent discussion has (for me at least) made it plain what the Law should be.