Bool DMXGetDesktopAttributes(Display *dpy, DMXDesktopAttributes *attr);
typedef struct { unsigned int width; unsigned int height; int shiftX; int shiftY; } DMXDesktopAttributes;
The size of the global bounding box is given in width, and height. The shiftX and shiftY values will always be 0. The global bounding box is computed whether or not Xinerama is active, but it is only useful when using Xinerama.
The global bounding box used by Xdmx(1) may be larger than the Xinerama screen size because of information in the configuration file.