A folder took a form of a vertical "task bar" on the left side of screen. How to reverse it?

Question

I don't understand what happened: Somehow my son opened his folder on the laptop and clicked somewhere, now the folder always appears in the form of a vertical bar on the left side of my desktop:

Is there any way I could get rid of that? I am using Windows XP

Answer 1

This can be done with any folder by simply dragging it to the edge of the screen and letting go. To remove it from the Desktop, right-click on it (in a blank space on the bar, not on an icon) and choose "Close Toolbar."