Use of ABM_SETAUTOHIDEBAREX

Question

How do I use SHAppBarMessage with ABM_SETAUTOHIDEBAREXcorrectly?

Documentation of APPBARDATA structure says:

rc

Type: RECT

A RECT structure whose use varies depending on the message:

• ABM_GETTASKBARPOS, ABM_QUERYPOS, ABM_SETPOS: The bounding rectangle, in screen coordinates, of an appbar or the Windows taskbar.
• ABM_GETAUTOHIDEBAREX, ABM_SETAUTOHIDEBAREX: The monitor on which the operation is being performed.

But how do I specify a monitor as RECT? I tried with workarea/screen coordinates - no luck.

What are the requirements for ABM_SETAUTOHIDEBAREX to work? Win7? Vista?