When you move your mouse cursor over the taskbar icons, you see the thumnail views.

Here is a simple to achieve the same with the help of the keyboard, keep pressing the Windows+T key and you will see the focus shifting from the left most icon and moving towards the right side.

Or just press Windows+T once and leave.

Then use the arrow keys to move focus.

If you have liked this post, you might want to check out some more, on topics like Icons, Keyboard, Taskbar, Thumbnails, Tips.