#include <stdio.h> 
#include <stdlib.h> 
#include <windows.h> 

...
typedef struct _GDI_TABLE_ENTRY
{
   PVOID pKernelInfo;
   WORD  ProcessID; 
   WORD  _nCount;
   WORD  nUpper;
   BYTE  nType;
   BYTE  flags;
   PVOID pUserInfo;
} GDI_TABLE_ENTRY, *PGDI_TABLE_ENTRY;
...