That's an intended behavior.
First, when a Metro app process is killed, the taskbar button doesn't go away. You can try it and see.
Second, I'm not sure how Metro app processes are implemented. Perhaps it's possible that two apps share the same process, I don't know.
Why would you want such functionality? As far as I know, Metro apps don't tend to hand like native apps sometimes do, so it's usually enough to just close them.

Yes, you can create a shortcut with a predefined AppID. A tool which can help you with this is win7appid.

OK, I think I understand what you're looking for. Basically, what you want is the random_group_xxx AppID.

I'll explain what happens in that video you've posted (you'll understand it better if you'll open Taskbar Inspector and look at the AppIDs):

1. You're opening a Notepad instance, with the AppID, say, notepad_id.
2. You're opening a Calculator instance, with the AppID, say, calculator_id.
3. You're merging Calculator into the group of Notepad, which makes them both with the AppID of notepad_id.
4. (then you're launching another Calculator instance; not interesting)
5. You're launching another Notepad instance, with the AppID of notepad_id. Because the Notepad+Calculator group has the AppID of notepad_id, the new Notepad instance groups with the existing group.

Similar thing happens later, when Calculator groups into an existing group.

Solution: create a random group, i.e. a group with the AppID of random_group_xxx.
How to do that: say you have a button of Notepad and of Calculator. First, change one of them (say, Notepad) to have the random_group_xxx AppID. You can do this by right-click-dragging the button outside the taskbar. Then, merge the Calculator button with the Notepad button, which is now with the AppID of random_group_xxx. You'll get a random group, which will not have new instances of Notepad or Calculator grouped with, unless you choose to do so manually.

Wow, that turned out to be a lot of text. I hope I managed to clarify a thing or two.

Currently, that's not possible.

Sorry, but I don't understand what you mean. Could you perhaps post an image that explains it?

Is your goal to have these custom groups (e.g. Calculator + Notepad) temporarily, or do you want them to be grouped every time you launch them?
If it's the former, I don't understand your statement about having to "exclude" every application. Can you please clarify what you mean?

Disable it globally, and enable it selectively. Unless I'm missing your point?

Do you mean this?


If yes, you can see the solution here:
http://superuser.com/a/831516

Похожий вопрос был тут:
http://rammichael.com/7-taskbar-tweaker/comment-page-17#comment-3660
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