Index: Makefile.in
==================================================================
--- Makefile.in
+++ Makefile.in
@@ -417,10 +417,11 @@
   $(TOP)/src/test_tclsh.c \
   $(TOP)/src/test_tclvar.c \
   $(TOP)/src/test_thread.c \
   $(TOP)/src/test_vfs.c \
   $(TOP)/src/test_windirent.c \
+  $(TOP)/src/test_window.c \
   $(TOP)/src/test_wsd.c       \
   $(TOP)/ext/fts3/fts3_term.c \
   $(TOP)/ext/fts3/fts3_test.c  \
   $(TOP)/ext/session/test_session.c \
   $(TOP)/ext/rbu/test_rbu.c 

Index: Makefile.msc
==================================================================
--- Makefile.msc
+++ Makefile.msc
@@ -1477,10 +1477,11 @@
   $(TOP)\src\test_tclsh.c \
   $(TOP)\src\test_tclvar.c \
   $(TOP)\src\test_thread.c \
   $(TOP)\src\test_vfs.c \
   $(TOP)\src\test_windirent.c \
+  $(TOP)\src\test_window.c \
   $(TOP)\src\test_wsd.c \
   $(TOP)\ext\fts3\fts3_term.c \
   $(TOP)\ext\fts3\fts3_test.c \
   $(TOP)\ext\rbu\test_rbu.c \
   $(TOP)\ext\session\test_session.c

Index: main.mk
==================================================================
--- main.mk
+++ main.mk
@@ -347,10 +347,11 @@
   $(TOP)/src/test_tclsh.c \
   $(TOP)/src/test_tclvar.c \
   $(TOP)/src/test_thread.c \
   $(TOP)/src/test_vfs.c \
   $(TOP)/src/test_windirent.c \
+  $(TOP)/src/test_window.c \
   $(TOP)/src/test_wsd.c
 
 # Extensions to be statically loaded.
 #
 TESTSRC += \

Index: src/func.c
==================================================================
--- src/func.c
+++ src/func.c
@@ -1769,14 +1769,14 @@
   if( caseSensitive ){
     pInfo = (struct compareInfo*)&likeInfoAlt;
   }else{
     pInfo = (struct compareInfo*)&likeInfoNorm;
   }
-  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
-  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0);
+  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
+  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
   sqlite3CreateFunc(db, "glob", 2, SQLITE_UTF8, 
-      (struct compareInfo*)&globInfo, likeFunc, 0, 0, 0);
+      (struct compareInfo*)&globInfo, likeFunc, 0, 0, 0, 0, 0);
   setLikeOptFlag(db, "glob", SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE);
   setLikeOptFlag(db, "like", 
       caseSensitive ? (SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE) : SQLITE_FUNC_LIKE);
 }
 

Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -1681,10 +1681,12 @@
   int enc,
   void *pUserData,
   void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
   void (*xStep)(sqlite3_context*,int,sqlite3_value **),
   void (*xFinal)(sqlite3_context*),
+  void (*xValue)(sqlite3_context*),
+  void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
   FuncDestructor *pDestructor
 ){
   FuncDef *p;
   int nName;
   int extraFlags;
@@ -1714,14 +1716,14 @@
   if( enc==SQLITE_UTF16 ){
     enc = SQLITE_UTF16NATIVE;
   }else if( enc==SQLITE_ANY ){
     int rc;
     rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8|extraFlags,
-         pUserData, xSFunc, xStep, xFinal, pDestructor);
+         pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
     if( rc==SQLITE_OK ){
       rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE|extraFlags,
-          pUserData, xSFunc, xStep, xFinal, pDestructor);
+          pUserData, xSFunc, xStep, xFinal, xValue, xInverse, pDestructor);
     }
     if( rc!=SQLITE_OK ){
       return rc;
     }
     enc = SQLITE_UTF16BE;
@@ -1763,42 +1765,36 @@
   p->u.pDestructor = pDestructor;
   p->funcFlags = (p->funcFlags & SQLITE_FUNC_ENCMASK) | extraFlags;
   testcase( p->funcFlags & SQLITE_DETERMINISTIC );
   p->xSFunc = xSFunc ? xSFunc : xStep;
   p->xFinalize = xFinal;
+  p->xValue = xValue;
+  p->xInverse = xInverse;
   p->pUserData = pUserData;
   p->nArg = (u16)nArg;
   return SQLITE_OK;
 }
 
 /*
-** Create new user functions.
+** Worker function used by utf-8 APIs that create new functions:
+**
+**    sqlite3_create_function()
+**    sqlite3_create_function_v2()
+**    sqlite3_create_window_function()
 */
-int sqlite3_create_function(
+static int createFunctionApi(
   sqlite3 *db,
   const char *zFunc,
   int nArg,
   int enc,
   void *p,
-  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
-  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
-  void (*xFinal)(sqlite3_context*)
-){
-  return sqlite3_create_function_v2(db, zFunc, nArg, enc, p, xSFunc, xStep,
-                                    xFinal, 0);
-}
-
-int sqlite3_create_function_v2(
-  sqlite3 *db,
-  const char *zFunc,
-  int nArg,
-  int enc,
-  void *p,
-  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
-  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
   void (*xFinal)(sqlite3_context*),
-  void (*xDestroy)(void *)
+  void (*xValue)(sqlite3_context*),
+  void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
+  void(*xDestroy)(void*)
 ){
   int rc = SQLITE_ERROR;
   FuncDestructor *pArg = 0;
 
 #ifdef SQLITE_ENABLE_API_ARMOR
@@ -1816,11 +1812,13 @@
     }
     pArg->nRef = 0;
     pArg->xDestroy = xDestroy;
     pArg->pUserData = p;
   }
-  rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, xSFunc, xStep, xFinal, pArg);
+  rc = sqlite3CreateFunc(db, zFunc, nArg, enc, p, 
+      xSFunc, xStep, xFinal, xValue, xInverse, pArg
+  );
   if( pArg && pArg->nRef==0 ){
     assert( rc!=SQLITE_OK );
     xDestroy(p);
     sqlite3_free(pArg);
   }
@@ -1828,10 +1826,56 @@
  out:
   rc = sqlite3ApiExit(db, rc);
   sqlite3_mutex_leave(db->mutex);
   return rc;
 }
+
+/*
+** Create new user functions.
+*/
+int sqlite3_create_function(
+  sqlite3 *db,
+  const char *zFunc,
+  int nArg,
+  int enc,
+  void *p,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*)
+){
+  return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
+                                    xFinal, 0, 0, 0);
+}
+int sqlite3_create_function_v2(
+  sqlite3 *db,
+  const char *zFunc,
+  int nArg,
+  int enc,
+  void *p,
+  void (*xSFunc)(sqlite3_context*,int,sqlite3_value **),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*),
+  void (*xDestroy)(void *)
+){
+  return createFunctionApi(db, zFunc, nArg, enc, p, xSFunc, xStep,
+                                    xFinal, 0, 0, xDestroy);
+}
+int sqlite3_create_window_function(
+  sqlite3 *db,
+  const char *zFunc,
+  int nArg,
+  int enc,
+  void *p,
+  void (*xStep)(sqlite3_context*,int,sqlite3_value **),
+  void (*xFinal)(sqlite3_context*),
+  void (*xValue)(sqlite3_context*),
+  void (*xInverse)(sqlite3_context*,int,sqlite3_value **),
+  void (*xDestroy)(void *)
+){
+  return createFunctionApi(db, zFunc, nArg, enc, p, 0, xStep,
+                                    xFinal, xValue, xInverse, xDestroy);
+}
 
 #ifndef SQLITE_OMIT_UTF16
 int sqlite3_create_function16(
   sqlite3 *db,
   const void *zFunctionName,
@@ -1849,11 +1893,11 @@
   if( !sqlite3SafetyCheckOk(db) || zFunctionName==0 ) return SQLITE_MISUSE_BKPT;
 #endif
   sqlite3_mutex_enter(db->mutex);
   assert( !db->mallocFailed );
   zFunc8 = sqlite3Utf16to8(db, zFunctionName, -1, SQLITE_UTF16NATIVE);
-  rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0);
+  rc = sqlite3CreateFunc(db, zFunc8, nArg, eTextRep, p, xSFunc,xStep,xFinal,0,0,0);
   sqlite3DbFree(db, zFunc8);
   rc = sqlite3ApiExit(db, rc);
   sqlite3_mutex_leave(db->mutex);
   return rc;
 }

Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -4738,10 +4738,22 @@
   void *pApp,
   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
   void (*xFinal)(sqlite3_context*),
   void(*xDestroy)(void*)
+);
+int sqlite3_create_window_function(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*),
+  void (*xValue)(sqlite3_context*),
+  void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
+  void(*xDestroy)(void*)
 );
 
 /*
 ** CAPI3REF: Text Encodings
 **

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -4242,11 +4242,14 @@
 #ifdef SQLITE_DEBUG
 int sqlite3KeyInfoIsWriteable(KeyInfo*);
 #endif
 int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *,
   void (*)(sqlite3_context*,int,sqlite3_value **),
-  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
+  void (*)(sqlite3_context*,int,sqlite3_value **), 
+  void (*)(sqlite3_context*),
+  void (*)(sqlite3_context*),
+  void (*)(sqlite3_context*,int,sqlite3_value **), 
   FuncDestructor *pDestructor
 );
 void sqlite3NoopDestructor(void*);
 void sqlite3OomFault(sqlite3*);
 void sqlite3OomClear(sqlite3*);

Index: src/test_tclsh.c
==================================================================
--- src/test_tclsh.c
+++ src/test_tclsh.c
@@ -103,10 +103,11 @@
 #endif
 #ifdef SQLITE_ENABLE_ZIPVFS
   extern int Zipvfs_Init(Tcl_Interp*);
 #endif
   extern int TestExpert_Init(Tcl_Interp*);
+  extern int Sqlitetest_window_Init(Tcl_Interp *);
 
   Tcl_CmdInfo cmdInfo;
 
   /* Since the primary use case for this binary is testing of SQLite,
   ** be sure to generate core files if we crash */
@@ -167,10 +168,11 @@
 
 #if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
   Sqlitetestfts3_Init(interp);
 #endif
   TestExpert_Init(interp);
+  Sqlitetest_window_Init(interp);
 
   Tcl_CreateObjCommand(
       interp, "load_testfixture_extensions", load_testfixture_extensions,0,0
   );
   return 0;

ADDED   src/test_window.c
Index: src/test_window.c
==================================================================
--- src/test_window.c
+++ src/test_window.c
@@ -0,0 +1,194 @@
+/*
+** 2018 June 17
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+
+#include "sqlite3.h"
+
+#ifdef SQLITE_TEST
+
+#include "sqliteInt.h"
+#include <tcl.h>
+
+extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
+extern const char *sqlite3ErrName(int);
+
+typedef struct TestWindow TestWindow;
+struct TestWindow {
+  Tcl_Obj *xStep;
+  Tcl_Obj *xFinal;
+  Tcl_Obj *xValue;
+  Tcl_Obj *xInverse;
+  Tcl_Interp *interp;
+};
+
+typedef struct TestWindowCtx TestWindowCtx;
+struct TestWindowCtx {
+  Tcl_Obj *pVal;
+};
+
+static void doTestWindowStep(
+  int bInverse,
+  sqlite3_context *ctx, 
+  int nArg, 
+  sqlite3_value **apArg
+){
+  int i;
+  TestWindow *p = (TestWindow*)sqlite3_user_data(ctx);
+  Tcl_Obj *pEval = Tcl_DuplicateObj(bInverse ? p->xInverse : p->xStep);
+  TestWindowCtx *pCtx = sqlite3_aggregate_context(ctx, sizeof(TestWindowCtx));
+
+  Tcl_IncrRefCount(pEval);
+  if( pCtx ){
+    const char *zResult;
+    int rc;
+    if( pCtx->pVal ){
+      Tcl_ListObjAppendElement(p->interp, pEval, Tcl_DuplicateObj(pCtx->pVal));
+    }else{
+      Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj("", -1));
+    }
+    for(i=0; i<nArg; i++){
+      Tcl_Obj *pArg;
+      pArg = Tcl_NewStringObj((const char*)sqlite3_value_text(apArg[i]), -1);
+      Tcl_ListObjAppendElement(p->interp, pEval, pArg);
+    }
+    rc = Tcl_EvalObjEx(p->interp, pEval, TCL_EVAL_GLOBAL);
+    if( rc!=TCL_OK ){
+      zResult = Tcl_GetStringResult(p->interp);
+      sqlite3_result_error(ctx, zResult, -1);
+    }else{
+      if( pCtx->pVal ) Tcl_DecrRefCount(pCtx->pVal);
+      pCtx->pVal = Tcl_DuplicateObj(Tcl_GetObjResult(p->interp));
+      Tcl_IncrRefCount(pCtx->pVal);
+    }
+  }
+  Tcl_DecrRefCount(pEval);
+}
+
+static void doTestWindowFinalize(int bValue, sqlite3_context *ctx){
+  TestWindow *p = (TestWindow*)sqlite3_user_data(ctx);
+  Tcl_Obj *pEval = Tcl_DuplicateObj(bValue ? p->xValue : p->xFinal);
+  TestWindowCtx *pCtx = sqlite3_aggregate_context(ctx, sizeof(TestWindowCtx));
+
+  Tcl_IncrRefCount(pEval);
+  if( pCtx ){
+    const char *zResult;
+    int rc;
+    if( pCtx->pVal ){
+      Tcl_ListObjAppendElement(p->interp, pEval, Tcl_DuplicateObj(pCtx->pVal));
+    }else{
+      Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj("", -1));
+    }
+
+    rc = Tcl_EvalObjEx(p->interp, pEval, TCL_EVAL_GLOBAL);
+    zResult = Tcl_GetStringResult(p->interp);
+    if( rc!=TCL_OK ){
+      sqlite3_result_error(ctx, zResult, -1);
+    }else{
+      sqlite3_result_text(ctx, zResult, -1, SQLITE_TRANSIENT);
+    }
+
+    if( bValue==0 ){
+      if( pCtx->pVal ) Tcl_DecrRefCount(pCtx->pVal);
+      pCtx->pVal = 0;
+    }
+  }
+  Tcl_DecrRefCount(pEval);
+}
+
+static void testWindowStep(
+  sqlite3_context *ctx, 
+  int nArg, 
+  sqlite3_value **apArg
+){
+  doTestWindowStep(0, ctx, nArg, apArg);
+}
+static void testWindowInverse(
+  sqlite3_context *ctx, 
+  int nArg, 
+  sqlite3_value **apArg
+){
+  doTestWindowStep(1, ctx, nArg, apArg);
+}
+
+static void testWindowFinal(sqlite3_context *ctx){
+  doTestWindowFinalize(0, ctx);
+}
+static void testWindowValue(sqlite3_context *ctx){
+  doTestWindowFinalize(1, ctx);
+}
+
+static void testWindowDestroy(void *pCtx){
+  ckfree(pCtx);
+}
+
+/*
+** Usage: sqlite3_create_window_function DB NAME XSTEP XFINAL XVALUE XINVERSE
+*/
+static int SQLITE_TCLAPI test_create_window(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  TestWindow *pNew;
+  sqlite3 *db;
+  const char *zName;
+  int rc;
+
+  if( objc!=7 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME XSTEP XFINAL XVALUE XINVERSE");
+    return TCL_ERROR;
+  }
+
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+  zName = Tcl_GetString(objv[2]);
+  pNew = ckalloc(sizeof(TestWindow));
+  memset(pNew, 0, sizeof(TestWindow));
+  pNew->xStep = Tcl_DuplicateObj(objv[3]);
+  pNew->xFinal = Tcl_DuplicateObj(objv[4]);
+  pNew->xValue = Tcl_DuplicateObj(objv[5]);
+  pNew->xInverse = Tcl_DuplicateObj(objv[6]);
+  pNew->interp = interp;
+
+  Tcl_IncrRefCount(pNew->xStep);
+  Tcl_IncrRefCount(pNew->xFinal);
+  Tcl_IncrRefCount(pNew->xValue);
+  Tcl_IncrRefCount(pNew->xInverse);
+
+  rc = sqlite3_create_window_function(db, zName, -1, SQLITE_UTF8, (void*)pNew,
+      testWindowStep, testWindowFinal, testWindowValue, testWindowInverse,
+      testWindowDestroy
+  );
+  if( rc!=SQLITE_OK ){
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+    return TCL_ERROR;
+  }
+
+  return TCL_OK;
+}
+
+int Sqlitetest_window_Init(Tcl_Interp *interp){
+  static struct {
+     char *zName;
+     Tcl_ObjCmdProc *xProc;
+     int clientData;
+  } aObjCmd[] = {
+     { "sqlite3_create_window_function", test_create_window, 0 },
+  };
+  int i;
+  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
+    ClientData c = (ClientData)SQLITE_INT_TO_PTR(aObjCmd[i].clientData);
+    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, aObjCmd[i].xProc, c, 0);
+  }
+  return TCL_OK;
+}
+#endif

Index: src/vdbe.c
==================================================================
--- src/vdbe.c
+++ src/vdbe.c
@@ -6412,10 +6412,11 @@
   assert( pOp->p1>0 && pOp->p1<=(p->nMem+1 - p->nCursor) );
   pMem = &aMem[pOp->p1];
   assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
   if( pOp->p3 ){
     rc = sqlite3VdbeMemAggValue(pMem, &aMem[pOp->p3], pOp->p4.pFunc);
+    pMem = &aMem[pOp->p3];
   }else{
     rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc);
   }
   if( rc ){
     sqlite3VdbeError(p, "%s", sqlite3_value_text(pMem));

Index: src/window.c
==================================================================
--- src/window.c
+++ src/window.c
@@ -298,11 +298,11 @@
 ){
 }
 static void cume_distValueFunc(sqlite3_context *pCtx){
   struct CallCount *p;
   p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
-  if( p ){
+  if( p && p->nTotal ){
     double r = (double)(p->nStep) / (double)(p->nTotal);
     sqlite3_result_double(pCtx, r);
   }
 }
 
@@ -682,11 +682,10 @@
 */
 int sqlite3WindowRewrite(Parse *pParse, Select *p){
   int rc = SQLITE_OK;
   if( p->pWin ){
     Vdbe *v = sqlite3GetVdbe(pParse);
-    int i;
     sqlite3 *db = pParse->db;
     Select *pSub = 0;             /* The subquery */
     SrcList *pSrc = p->pSrc;
     Expr *pWhere = p->pWhere;
     ExprList *pGroupBy = p->pGroupBy;
@@ -741,12 +740,10 @@
         pParse, pSublist, pSrc, pWhere, pGroupBy, pHaving, pSort, 0, 0
     );
     p->pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
     assert( p->pSrc || db->mallocFailed );
     if( p->pSrc ){
-      int iTab;
-      ExprList *pList = 0;
       p->pSrc->a[0].pSelect = pSub;
       sqlite3SrcListAssignCursors(pParse, p->pSrc);
       if( sqlite3ExpandSubquery(pParse, &p->pSrc->a[0]) ){
         rc = SQLITE_NOMEM;
       }else{
@@ -1086,11 +1083,10 @@
   int lblFlushPart,               /* Subroutine to Gosub to */
   int *pRegSize                   /* OUT: Register containing partition size */
 ){
   Window *pMWin = p->pWin;
   Vdbe *v = sqlite3GetVdbe(pParse);
-  Window *pWin;
   int iSubCsr = p->pSrc->a[0].iCursor;
   int nSub = p->pSrc->a[0].pTab->nCol;
   int k;
 
   int reg = pParse->nMem+1;
@@ -1408,34 +1404,24 @@
   int regGosub, 
   int addrGosub
 ){
   Window *pMWin = p->pWin;
   Vdbe *v = sqlite3GetVdbe(pParse);
-  Window *pWin;
-  int k;
-  int nSub = p->pSrc->a[0].pTab->nCol;
   int regFlushPart;               /* Register for "Gosub flush_partition" */
   int lblFlushPart;               /* Label for "Gosub flush_partition" */
   int lblFlushDone;               /* Label for "Gosub flush_partition_done" */
 
   int regArg;
-  int nArg;
   int addr;
   int csrStart = pParse->nTab++;
   int csrEnd = pParse->nTab++;
   int regStart;                    /* Value of <expr> PRECEDING */
   int regEnd;                      /* Value of <expr> FOLLOWING */
-  int addrNext;
   int addrGoto;
   int addrTop;
   int addrIfPos1;
   int addrIfPos2;
-
-  int regPeer = 0;                 /* Number of peers in current group */
-  int regPeerVal = 0;              /* Array of values identifying peer group */
-  int iPeer = 0;                   /* Column offset in eph-table of peer vals */
-  int nPeerVal;                    /* Number of peer values */
   int regSize = 0;
 
   assert( pMWin->eStart==TK_PRECEDING 
        || pMWin->eStart==TK_CURRENT 
        || pMWin->eStart==TK_FOLLOWING 
@@ -1677,11 +1663,10 @@
   int regGosub, 
   int addrGosub
 ){
   Window *pMWin = p->pWin;
   Vdbe *v = sqlite3GetVdbe(pParse);
-  Window *pWin;
   int k;
   int addr;
   ExprList *pPart = pMWin->pPartition;
   ExprList *pOrderBy = pMWin->pOrderBy;
   int nPeer = pOrderBy ? pOrderBy->nExpr : 0;
@@ -1693,11 +1678,10 @@
   int lblFlushPart;
   int csrLead;
   int regCtr;
   int regArg;                     /* Register array to martial function args */
   int regSize;
-  int nArg;
   int lblEmpty;
   int bReverse = pMWin->pOrderBy && pMWin->eStart==TK_CURRENT 
           && pMWin->eEnd==TK_UNBOUNDED;
 
   assert( (pMWin->eStart==TK_UNBOUNDED && pMWin->eEnd==TK_CURRENT) 
@@ -1820,11 +1804,10 @@
   int regGosub, 
   int addrGosub
 ){
   Window *pMWin = p->pWin;
   Vdbe *v = sqlite3GetVdbe(pParse);
-  Window *pWin;
   int k;
   int iSubCsr = p->pSrc->a[0].iCursor;
   int nSub = p->pSrc->a[0].pTab->nCol;
   int reg = pParse->nMem+1;
   int regRecord = reg+nSub;

Index: test/window1.test
==================================================================
--- test/window1.test
+++ test/window1.test
@@ -267,8 +267,15 @@
 
 do_execsql_test 7.3 {
   SELECT row_number() OVER (ORDER BY x) FROM t1
 } {1 2 3 4 5}
 
+do_execsql_test 7.4 {
+  SELECT 
+    row_number() OVER win,
+    lead(x) OVER win
+  FROM t1
+  WINDOW win AS (ORDER BY x ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
+} {1 3  2 5  3 7  4 9   5 {}}
 
 finish_test
 

ADDED   test/window5.test
Index: test/window5.test
==================================================================
--- test/window5.test
+++ test/window5.test
@@ -0,0 +1,68 @@
+# 2018 May 8
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library. Specifically,
+# it tests the sqlite3_create_window_function() API.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+set testprefix window1
+
+proc m_step {ctx val} {
+  lappend ctx $val
+  return $ctx
+}
+proc m_value {ctx} {
+  set lSort [lsort $ctx]
+
+  set nVal [llength $lSort]
+  set n [expr $nVal/2]
+  
+  if {($nVal % 2)==0 && $nVal>0} {
+    set a [lindex $lSort $n]
+    set b [lindex $lSort $n-1]
+    if {($a+$b) % 2} {
+      set ret [expr ($a+$b)/2.0]
+    } else {
+      set ret [expr ($a+$b)/2]
+    }
+  } else {
+    set ret [lindex $lSort $n]
+  }
+  return $ret
+}
+proc m_inverse {ctx val} {
+  set ctx [lrange $ctx 1 end]
+  return $ctx
+}
+proc w_value {ctx} {
+  lsort $ctx
+}
+
+sqlite3_create_window_function db median m_step m_value m_value m_inverse
+sqlite3_create_window_function db win m_step w_value w_value m_inverse
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b);
+  INSERT INTO t1 VALUES(4, 'a');
+  INSERT INTO t1 VALUES(6, 'b');
+  INSERT INTO t1 VALUES(1, 'c');
+  INSERT INTO t1 VALUES(5, 'd');
+  INSERT INTO t1 VALUES(2, 'e');
+  INSERT INTO t1 VALUES(3, 'f');
+}
+
+do_execsql_test 1.1 {
+  SELECT win(a) OVER (ORDER BY b), median(a) OVER (ORDER BY b) FROM t1;
+} {4 4  {4 6} 5  {1 4 6} 4  {1 4 5 6} 4.5  {1 2 4 5 6} 4 {1 2 3 4 5 6} 3.5}
+
+finish_test
+