Process Explorer - How does the dragabble crosshair work?

There is a feature in sysinternal's process explorer that allows a crosshair to be dragged from the application to a control in any other application you are running and highlights said control. Does anyone know how this was achieved or if there is a .NET/C++ library out there that can be reused?

From stackoverflow

• Using Win32 API

  • GetCursorPos: to get the cursor position (maybe .NET has its own function to do that)
  • WindowFromPoint: to get the handle of the window from a specific point in the screen

  more info

  John Dibling : That's all there is to it; I wonder why this hasn't been accepted yet.