In modern Windows, when an app opens multiple windows, they stack on the same icon on the task bar. The most common example would be MS Word or IE.
When you use Win+NumberKeys to quickly access taskbar apps, you can keep pressing the same number to switch between these opened windows.
I have an app that I use extremely often everyday and I put it on Win-1. But what I truly use extremely often is the secondary window it opens, which I have to press Win-1-1 to get to. I can't manually change the order of these two windows like MS Word or IE, because the secondary is secondary, and the primary can't be closed. However, occasionally (about once a week) these two windows will switch orders, so Win-1-1 becomes Win-1, which makes me really happy, but I have no idea how it happened. Does anybody know how to manually make it happen?
when an app opens multiple windows, they stack on the same icon on the task bar
no, if you select combine taskbar buttons when taskbar is full or never, it'll be different buttons