Odds are that Gunnar doesnt feel the need to bark when you're around because he's comfortable. When he's alone and there's strange people poking in at the windows he goes into defense because he broke past his comfort level. Now he's, well, I don't wanna say scared, but thats essentially where defense comes from, so the barking starts, maybe hackling, maybe showing teeth etc. Ofcourse, there is still glass and doors between the dog and the people, so he is more confident to act like a badass. Now, if someone actually comes into the house then its likely the dog will change his tune when he realizes he's no longer protected by glass and doors, he'll probably stand back at a distance and bark.
Will someone go into a house with a barking dog? Unlikely.
1) a lot of smoke in your house
The pups: Probably be totally oblivious to the smoke being there and hunt around sniffing this unusual new smell.
Lyka: Hackles up, bark, pause, cautiously approach with little barks, realize its nothing, walk away and do something else.
Cujo: Approach cautiously, realize its nothing, get on with life.
2) Your long lost sister comes over after 20 years and brings her 5 very young, wild, screaming, running, unruly children in tow and your dog has never really been around kids before
Pups: They'd love the chaotic mess, jump on all the kids, lick them to death, wag their tails furiously and scratch the hell out of everyone in the room.
Lyka: She'd bark at them for 3 days straight.
Cujo: Run around in circles around everyone, get too excited and try to nip them in the face or nip at their clothing.
Pups: Couldn't care less, they love everyone and everything. Its sickening how happy and upbeat they are :p
Lyka: She'll deal with it, won't like anyone, but will walk around on a leash.
Cujo: He won't eat more than a few bites, only after he hasnt eaten for a few days, and be really depressed.
4) you bring your dog to an unknown area - doggie heaven where it's free to run like he/she has never run before - acres of fields - and your dog is suddenly, mistakenly off leash and free to run from you if he/she wanted. Add a strange distraction, maybe cows (if he/she has never seen them before) are in the field or whatever.
Tiko: Run around like an idiot for a while, slow down, walk around sniffing everything, bark at the cows.
Yasko: Walk around sniffing and checking everything out. Bark at cows.
Lyka: Run around, find something that looks like a ball, drop it at my feet and bark at me to throw it. Ignore the cows.
Cujo: Charge at the cows, then when the cow turns around and runs at him he will go "OH S***!!". Yes, this happened last year when he crawled under my neighbors barb wire fence.
5) A wild parade where the people are wearing wild costumes that make the people gigantic in stature, you've seen them, just wild costumes and one approached your dog.
Lyka: She won't shut up.
Pups: Probably act really excited and upbeat and happy and want to bite the costumes.
Cujo: He'll be completely indifferent to it and probably find something that's been peed on to sniff and then pee on himself.