taskbar: show list instead of preview screenshots

Hello, I just noticed that if I open LOTS of windows of the same app, there will not longer be a horizontal row of screenshots previewing them, but a vertical list, when I click on the program's taskbar icon.

Is there a way to enforce that list even if there are just a few windows, e.g. via registry or group policy?

Thank you!

Not as far as I know, but I may be wrong. MS do not like things changed on the taskbar

I get both. If I just hover over the icons in the task bar, I see small screen shots of the files that are open. But if I right click on the task bar icon, the display shifts to a vertical list. The vertical list often includes a list of previous files that were opened by a particular application.