No, actually the Glock has NO external safety switch at all, nor does it have a "decocker", nor is it truly DAO.
The Glock has what they call a "safe action trigger". What this means is that when a cop shoots himself in the ass or shoots an innocent bystander due to a ND, he will be safe from prosecution, sanction, or restriction. But when a citizen has an ND with a Glock, the system will spring into action to prosecute him to the fullest extent of the law.. </sarcasm>
Actually, I own and carry a Glock 36. I carried it for two months without a round in the tube, because I wasn't terribly comfortable with it in the Serpa, knowing what I know about Glocks (I worked for the DOJ in the DC area during the time when DC Metro PD was switching over from revolvers to Glocks, and they had over 100 NDs in the first few years of carrying the Glock). But now that I've owned it for several months, and put several hundred rounds through it, I feel safe with the firearm's "safety" mechanisms, the holster, and my abilities to handle it safely.
The key to handling a Glock with "one in the chamber" is training. If you keep your booger hook off the bang switch while drawing and re-holstering a Glock, it's just as safe as any other firearm. The grip angle and trigger geometry are SUBSTANTIALLY different from a 1911, and manipulating a Glock in and out of a holster requires a slight modification in trigger-finger position when using a Serpa. A few thousand presentation drills will imprint this difference on your muscle memory though...
All that said, I would NEVER leave a "hot" Glock in an unsecured location in my house. It's either on my hip, or unloaded and locked up. The functionality of the Glock makes it just TOO prone to ND in untrained hands to be trusted in unsupervised or untrained hands.