I'm using 3.4.7.2 verion of Openbox in Debian Lenny. Screen has been configured to be 1280x1024. I have two panels on the desktop - at the top of the screen (80 pixels height) and at the bottom (96 pixels height). Both panels are DOCKs and use STRUTs. According to fd.o, 

"The Window Manager SHOULD calculate this space by taking the current page minus space occupied by dock and panel windows, as indicated by the _NET_WM_STRUT or _NET_WM_STRUT_PARTIAL properties set on client windows."

As a result, NET_WORKAREA must have the following geometry: x=0, y=80 w=1280, h=848 (1024-80-96). But it has wrong geometry: x=0, y=80 w=1280, h=944 (1024-80). As you can see, the size of bottom panel is not counted. It blocks getting right geometry of the desktop.