Why do pinned apps sometimes go to the end of the taskbar, rather than going into the “pinned apps” section of the taskbar?
You may have noticed that the apps you’ve pinned to the taskbar are on the left, and the regular apps are on the right.¹ But sometimes, a pinned app goes to the right. Why is that?
There is no “pinned apps” section of the taskbar. The taskbar just has one area for apps, and some of the apps are pinned, and some of the apps are not pinned. Now, it so happens that over time, pinned apps tend to migrate to the left. But that’s an artifact of the behavior of the taskbar, not because there’s a “pinned apps” section.
Let’s see how things turn out the way they do.
First, observe that new apps go at the end.
Second, pinned apps stay on the taskbar even if the app isn’t running.
These two rules together mean that pinned apps will tend to move toward the left: If there is a non-pinned app on the taskbar, it will get closed eventually, and then it loses its spot. When the app is relaunched, it goes back to the end.
Imagine an organization where some members have access to sabbatical leave and others do not. Furthermore, suppose that offices are assigned in seniority order. You end up with all the best offices going to people who have access to sabbatical leave, even though that was never actually written into the rules.
You get this phenomenon because people with sabbatical leave can take a leave without losing their seniority. Whereas people without access to sabbatical leave have no choice but to resign, and then rejoin the organization later, which puts them back at the bottom of the seniority list.
The “pinned apps” area is an analogous phenomenon: Since pinned apps never lose their place, whereas unpinned apps lose their place when they are closed, you end up with the pinned apps gravitating toward the left.
Once you realize that this is is an emergent behavior, you can easily come up with a way for a pinned app to end up to the right of an unpinned app: The app was originally not pinned, and then you pinned it. Pinning an app does not move it, so it remains where it is, which is near the end of the taskbar.
Of course, as you close unpinned apps that exist to the left of the newly-pinned app, the newly-pinned app will slide left one slot, and over time it will eventually find itself next to the other pinned apps.
But it’s not like there’s a special “pinned apps” section. It’s just that pinned apps tend to have the highest seniority because they never lose their place.
¹ At least, that’s how it is for left-to-right languages. For right-to-left languages, it’s the other way around. More precisely, “You may have noticed that all the apps you’ve pinned to the taskbar are on the side closer to the Start button, and all the regular apps are on the side closer to the notification icons and the clock.”