A XLayerUtil.h

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xmd.h>

/* Transparent type values */
/*      None                  0 */
#define TransparentPixel      1
#define TransparentMask       2

/* layered visual info template flags */
#define VisualLayerMask         0x200
#define VisualTransparentType   0x400
#define VisualTransparentValue  0x800
#define VisualAllLayerMask      0xFFF

/* layered visual info structure */
typedef struct _XLayerVisualInfo {
   XVisualInfo vinfo;
   long layer;
   long type;
   unsigned long value;
} XLayerVisualInfo;

/* SERVER_OVERLAY_VISUALS property element */
typedef struct _OverlayInfo {
   /* Avoid 64-bit portability problems by being careful to use
      longs due to the way XGetWindowProperty is specified. Note
      that these parameters are passed as CARD32s over X
      protocol. */
   long  overlay_visual;
   long  transparent_type;
   long  value;
   long  layer;
} OverlayInfo;

extern XLayerVisualInfo *XGetLayerVisualInfo(Display*,long,XLayerVisualInfo*,int*);
extern Status XMatchLayerVisualInfo(Display*,int,int,int,int,XLayerVisualInfo*);