To all that say Glock, do a search for the ND poll on this forum. There were more "oops, the hammer slipped while I was decocking" ND's than all the ND's that were even possible to attribute to a lack of a manual safety! Since the Glock doesn't have an external hammer, it's safe to say Glock ain't it. And in the comments, 1911's and revolvers were implicated many times more often than Glocks. 1911's seem to be the #1 creators of unwanted holes in bedroom walls.
What makes the Glock so safe is a simple manual of arms, a chunky trigger guard, and a heavy trigger pull (esp compared to the weight of the gun). It's hard enough to pull a Glock trigger on purpose. You can put your finger in the triggerguard and spin and shake a stock Glock (with empty chamber) all around, and the trigger will not break.
Now take a 3 lb gun with a 3-5 lb hair trigger, a rail thin trigger guard, an external hammer for the Curious George to mess with, and tack on a manual safety for peace of mind. Now that's an ND waiting to happen.
Sure, a Glock is more prone to freak holster strap or other holster malfunctions due to lack of safety. But I'll bet those type of malfunctions account for less than 0.1% of all ND's. It's complete and utter nonsense to look at the "what if" holster strap/shirt tail scenarios and to blame them for the world's ND problems. It doesn't add up.
The field stripping argument, I don't have as good an answer for. But I've read of only 1 single claim of ND while field stripping. And it was probably just CYA, because it sounded better than "well, I was playing with my gun..."