diff --git a/reactos/win32ss/gdi/ntgdi/bitblt.c b/reactos/win32ss/gdi/ntgdi/bitblt.c
index a408509234d..760c2457d63 100644
--- a/reactos/win32ss/gdi/ntgdi/bitblt.c
+++ b/reactos/win32ss/gdi/ntgdi/bitblt.c
@@ -1053,7 +1053,7 @@ IntGdiFillRgn(
 
     /* Transform region into device coordinates */
     if (!REGION_LPTODP(pdc, prgnClip, prgn) ||
-        REGION_iOffsetRgn(prgnClip, pdc->ptlDCOrig.x, pdc->ptlDCOrig.y) == ERROR)
+        !REGION_bOffsetRgn(prgnClip, pdc->ptlDCOrig.x, pdc->ptlDCOrig.y))
     {
         REGION_Delete(prgnClip);
         return FALSE;
diff --git a/reactos/win32ss/gdi/ntgdi/cliprgn.c b/reactos/win32ss/gdi/ntgdi/cliprgn.c
index e1627ed26c4..9f8b87e5a29 100644
--- a/reactos/win32ss/gdi/ntgdi/cliprgn.c
+++ b/reactos/win32ss/gdi/ntgdi/cliprgn.c
@@ -57,7 +57,7 @@ GdiSelectVisRgn(
     ASSERT(prgn != NULL);
 
     IntGdiCombineRgn(dc->prgnVis, prgn, NULL, RGN_COPY);
-    REGION_iOffsetRgn(dc->prgnVis, -dc->ptlDCOrig.x, -dc->ptlDCOrig.y);
+    REGION_bOffsetRgn(dc->prgnVis, -dc->ptlDCOrig.x, -dc->ptlDCOrig.y);
 
     DC_UnlockDc(dc);
 }
@@ -365,9 +365,17 @@ int APIENTRY NtGdiOffsetClipRgn(HDC  hDC,
 
     if(dc->dclevel.prgnClip != NULL)
     {
-        Result = REGION_iOffsetRgn(dc->dclevel.prgnClip,
-                                   XOffset,
-                                   YOffset);
+        if (!REGION_bOffsetRgn(dc->dclevel.prgnClip,
+                               XOffset,
+                               YOffset))
+        {
+            Result = ERROR;
+        }
+        else
+        {
+            Result = REGION_Complexity(dc->dclevel.prgnClip);
+        }
+
         dc->fs |= DC_FLAG_DIRTY_RAO;
     }
     else
@@ -572,7 +580,7 @@ CLIPPING_UpdateGCRegion(PDC pDC)
     }
 
 
-    REGION_iOffsetRgn(pDC->prgnRao, pDC->ptlDCOrig.x, pDC->ptlDCOrig.y);
+    REGION_bOffsetRgn(pDC->prgnRao, pDC->ptlDCOrig.x, pDC->ptlDCOrig.y);
 
     RtlCopyMemory(&pDC->erclClip,
                 &pDC->prgnRao->rdh.rcBound,
@@ -590,7 +598,7 @@ CLIPPING_UpdateGCRegion(PDC pDC)
                            pDC->prgnRao->Buffer,
                            &pDC->erclClip);
 
-    REGION_iOffsetRgn(pDC->prgnRao, -pDC->ptlDCOrig.x, -pDC->ptlDCOrig.y);
+    REGION_bOffsetRgn(pDC->prgnRao, -pDC->ptlDCOrig.x, -pDC->ptlDCOrig.y);
 }
 
 /* EOF */
diff --git a/reactos/win32ss/gdi/ntgdi/coord.h b/reactos/win32ss/gdi/ntgdi/coord.h
index c433f76cc3d..5e72d57cb39 100644
--- a/reactos/win32ss/gdi/ntgdi/coord.h
+++ b/reactos/win32ss/gdi/ntgdi/coord.h
@@ -1,5 +1,9 @@
 #pragma once
 
+/* Maximum extend of coordinate space */
+#define MIN_COORD (INT_MIN / 16)
+#define MAX_COORD (INT_MAX / 16)
+
 #define IntLPtoDP(pdc, ppt, count) DC_vXformWorldToDevice(pdc, count, (PPOINTL)(ppt), (PPOINTL)(ppt));
 #define CoordLPtoDP(pdc, ppt) DC_vXformWorldToDevice(pdc, 1,  (PPOINTL)(ppt), (PPOINTL)(ppt));
 #define IntDPtoLP(pdc, ppt, count) DC_vXformDeviceToWorld(pdc, count, (PPOINTL)(ppt), (PPOINTL)(ppt));
diff --git a/reactos/win32ss/gdi/ntgdi/dcobjs.c b/reactos/win32ss/gdi/ntgdi/dcobjs.c
index 6caeccd077c..15448670e3a 100644
--- a/reactos/win32ss/gdi/ntgdi/dcobjs.c
+++ b/reactos/win32ss/gdi/ntgdi/dcobjs.c
@@ -779,7 +779,10 @@ NtGdiGetRandomRgn(
         {
             ret = IntGdiCombineRgn(prgnDest, prgnSrc, 0, RGN_COPY) == ERROR ? -1 : 1;
             if ((ret == 1) && (iCode == SYSRGN))
-                REGION_iOffsetRgn(prgnDest, pdc->ptlDCOrig.x, pdc->ptlDCOrig.y);
+            {
+                /// \todo FIXME This is not really correct, since we already modified the region
+                ret = REGION_bOffsetRgn(prgnDest, pdc->ptlDCOrig.x, pdc->ptlDCOrig.y);
+            }
             REGION_UnlockRgn(prgnDest);
         }
         else
diff --git a/reactos/win32ss/gdi/ntgdi/region.c b/reactos/win32ss/gdi/ntgdi/region.c
index 561faa30073..d56028d9c42 100644
--- a/reactos/win32ss/gdi/ntgdi/region.c
+++ b/reactos/win32ss/gdi/ntgdi/region.c
@@ -514,7 +514,7 @@ REGION_CopyRegion(
     PREGION dst,
     PREGION src)
 {
-    /* Only copy if source and dest are equal */
+    /* Only copy if source and dest are not equal */
     if (dst != src)
     {
         /* Check if we need to increase our buffer */
@@ -1867,31 +1867,31 @@ REGION_bMakeFrameRegion(
     else
     {
         /* Move the source region to the bottom-right */
-        REGION_iOffsetRgn(prgnSrc, cx, cy);
+        REGION_bOffsetRgn(prgnSrc, cx, cy);
 
         /* Intersect with the source region (this crops the top-left frame) */
         REGION_IntersectRegion(prgnDest, prgnDest, prgnSrc);
 
         /* Move the source region to the bottom-left */
-        REGION_iOffsetRgn(prgnSrc, -2 * cx, 0);
+        REGION_bOffsetRgn(prgnSrc, -2 * cx, 0);
 
         /* Intersect with the source region (this crops the top-right frame) */
         REGION_IntersectRegion(prgnDest, prgnDest, prgnSrc);
 
         /* Move the source region to the top-left */
-        REGION_iOffsetRgn(prgnSrc, 0, -2 * cy);
+        REGION_bOffsetRgn(prgnSrc, 0, -2 * cy);
 
         /* Intersect with the source region (this crops the bottom-right frame) */
         REGION_IntersectRegion(prgnDest, prgnDest, prgnSrc);
 
         /* Move the source region to the top-right  */
-        REGION_iOffsetRgn(prgnSrc, 2 * cx, 0);
+        REGION_bOffsetRgn(prgnSrc, 2 * cx, 0);
 
         /* Intersect with the source region (this crops the bottom-left frame) */
         REGION_IntersectRegion(prgnDest, prgnDest, prgnSrc);
 
         /* Move the source region back to the original position */
-        REGION_iOffsetRgn(prgnSrc, -cx, cy);
+        REGION_bOffsetRgn(prgnSrc, -cx, cy);
 
         /* Finally subtract the cropped region from the source */
         REGION_SubtractRegion(prgnDest, prgnSrc, prgnDest);
@@ -1961,7 +1961,7 @@ REGION_bXformRgn(
         if (pmx->flAccel & XFORM_UNITY)
         {
             /* Just offset the region */
-            return REGION_iOffsetRgn(prgn, (pmx->fxDx + 8) / 16, (pmx->fxDy + 8) / 16) != ERROR;
+            return REGION_bOffsetRgn(prgn, (pmx->fxDx + 8) / 16, (pmx->fxDy + 8) / 16);
         }
         else
         {
@@ -2584,40 +2584,93 @@ REGION_SetRectRgn(
     }
 }
 
-INT
+BOOL
 FASTCALL
-REGION_iOffsetRgn(
-    PREGION rgn,
-    INT XOffset,
-    INT YOffset)
+REGION_bOffsetRgn(
+    _Inout_ PREGION prgn,
+    _In_ INT cx,
+    _In_ INT cy)
 {
-    if (XOffset || YOffset)
+    PRECTL prcl;
+    UINT i;
+
+    NT_ASSERT(prgn != NULL);
+
+    /* Check for trivial case */
+    if ((cx == 0) && (cy == 0))
     {
-        int nbox = rgn->rdh.nCount;
-        PRECTL pbox = rgn->Buffer;
+        return TRUE;
+    }
 
-        if (nbox && pbox)
+    /* Check for empty regions, we ignore the offset values here */
+    if (prgn->rdh.nCount == 0)
+    {
+        return TRUE;
+    }
+
+    /* Make sure the offset is within the legal range */
+    if ((cx > MAX_COORD) || (cx < MIN_COORD) ||
+        (cy > MAX_COORD) || (cy < MIN_COORD))
+    {
+        return FALSE;
+    }
+
+    /* Are we moving right? */
+    if (cx > 0)
+    {
+        /* Check if we stay inside the bounds on the right side */
+        if (prgn->rdh.rcBound.right > (MAX_COORD - cx))
         {
-            while (nbox--)
-            {
-                pbox->left += XOffset;
-                pbox->right += XOffset;
-                pbox->top += YOffset;
-                pbox->bottom += YOffset;
-                pbox++;
-            }
-
-            if (rgn->Buffer != &rgn->rdh.rcBound)
-            {
-                rgn->rdh.rcBound.left += XOffset;
-                rgn->rdh.rcBound.right += XOffset;
-                rgn->rdh.rcBound.top += YOffset;
-                rgn->rdh.rcBound.bottom += YOffset;
-            }
+            return FALSE;
+        }
+    }
+    else
+    {
+        /* Check if we stay inside the bounds on the left side */
+        if (prgn->rdh.rcBound.left < (MIN_COORD - cx))
+        {
+            return FALSE;
         }
     }
 
-    return REGION_Complexity(rgn);
+    /* Are we moving down? */
+    if (cy > 0)
+    {
+        /* Check if we stay inside the bounds on the right side */
+        if (prgn->rdh.rcBound.bottom > (MAX_COORD - cy))
+        {
+            return FALSE;
+        }
+    }
+    else
+    {
+        /* Check if we stay inside the bounds on the left side */
+        if (prgn->rdh.rcBound.top < (MIN_COORD - cy))
+        {
+            return FALSE;
+        }
+    }
+
+    /* Loop to move the rects */
+    prcl = prgn->Buffer;
+    for (i = 0; i < prgn->rdh.nCount; i++)
+    {
+        prcl[i].left += cx;
+        prcl[i].right += cx;
+        prcl[i].top += cy;
+        prcl[i].bottom += cy;
+    }
+
+    /* Finally update the bounds rect */
+    if (prgn->Buffer != &prgn->rdh.rcBound)
+    {
+        prgn->rdh.rcBound.left += cx;
+        prgn->rdh.rcBound.right += cx;
+        prgn->rdh.rcBound.top += cy;
+        prgn->rdh.rcBound.bottom += cy;
+    }
+
+    return TRUE;
 }
 
 /***********************************************************************
@@ -3786,7 +3839,14 @@ NtGdiOffsetRgn(
         return ERROR;
     }
 
-    ret = REGION_iOffsetRgn(rgn, XOffset, YOffset);
+    if (!REGION_bOffsetRgn(rgn, XOffset, YOffset))
+    {
+        ret = ERROR;
+    }
+    else
+    {
+        ret = REGION_Complexity(rgn);
+    }
 
     RGNOBJAPI_Unlock(rgn);
     return ret;
diff --git a/reactos/win32ss/gdi/ntgdi/region.h b/reactos/win32ss/gdi/ntgdi/region.h
index 51fa032fc80..101fe7263d9 100644
--- a/reactos/win32ss/gdi/ntgdi/region.h
+++ b/reactos/win32ss/gdi/ntgdi/region.h
@@ -62,7 +62,13 @@ GreCreatePolyPolygonRgn(
     _In_ ULONG cPolygons,
     _In_ INT iMode);
 
-INT FASTCALL REGION_iOffsetRgn(PREGION,INT,INT);
+BOOL
+FASTCALL
+REGION_bOffsetRgn(
+    _Inout_ PREGION prgn,
+    _In_ INT cx,
+    _In_ INT cy);
+
 BOOL FASTCALL IntRectInRegion(HRGN,LPRECTL);
 
 INT FASTCALL IntGdiCombineRgn(PREGION, PREGION, PREGION, INT);
diff --git a/reactos/win32ss/user/ntuser/painting.c b/reactos/win32ss/user/ntuser/painting.c
index 9fcc32e8103..30cee5a6bf9 100644
--- a/reactos/win32ss/user/ntuser/painting.c
+++ b/reactos/win32ss/user/ntuser/painting.c
@@ -460,11 +460,11 @@ IntInvalidateWindows(PWND Wnd, PREGION Rgn, ULONG Flags)
        PREGION RgnClip = RGNOBJAPI_Lock(Wnd->hrgnClip, NULL);
        if (RgnClip)
        {
-           REGION_iOffsetRgn(Rgn,
+           REGION_bOffsetRgn(Rgn,
                              -Wnd->rcWindow.left,
                              -Wnd->rcWindow.top);
            RgnType = IntGdiCombineRgn(Rgn, Rgn, RgnClip, RGN_AND);
-           REGION_iOffsetRgn(Rgn,
+           REGION_bOffsetRgn(Rgn,
                              Wnd->rcWindow.left,
                              Wnd->rcWindow.top);
            RGNOBJAPI_Unlock(RgnClip);
@@ -682,7 +682,7 @@ co_UserRedrawWindow(
           }
           else
           {
-              REGION_iOffsetRgn(TmpRgn, Window->rcClient.left, Window->rcClient.top);
+              REGION_bOffsetRgn(TmpRgn, Window->rcClient.left, Window->rcClient.top);
           }
       }
       else if (UpdateRect != NULL)
@@ -690,7 +690,7 @@ co_UserRedrawWindow(
          if (!RECTL_bIsEmptyRect(UpdateRect))
          {
             TmpRgn = IntSysCreateRectpRgnIndirect(UpdateRect);
-            REGION_iOffsetRgn(TmpRgn, Window->rcClient.left, Window->rcClient.top);
+            REGION_bOffsetRgn(TmpRgn, Window->rcClient.left, Window->rcClient.top);
          }
       }
       else if ((Flags & (RDW_INVALIDATE | RDW_FRAME)) == (RDW_INVALIDATE | RDW_FRAME) ||
@@ -1229,7 +1229,7 @@ co_UserGetUpdateRgn(PWND Window, PREGION Rgn, BOOL bErase)
     IntIntersectWithParents(Window, &Rect);
     REGION_SetRectRgn(Rgn, Rect.left, Rect.top, Rect.right, Rect.bottom);
     RegionType = IntGdiCombineRgn(Rgn, Rgn, UpdateRgn, RGN_AND);
-    REGION_iOffsetRgn(Rgn, -Window->rcClient.left, -Window->rcClient.top);
+    REGION_bOffsetRgn(Rgn, -Window->rcClient.left, -Window->rcClient.top);
     RGNOBJAPI_Unlock(UpdateRgn);
 
    if (bErase && RegionType != NULLREGION && RegionType != ERROR)
@@ -1565,7 +1565,7 @@ UserScrollDC(
 
       /* Substract the part of the dest that was visible in source */
       IntGdiCombineRgn(RgnTmp, RgnTmp, pDC->prgnVis, RGN_AND);
-      REGION_iOffsetRgn(RgnTmp, dx, dy);
+      REGION_bOffsetRgn(RgnTmp, dx, dy);
       Result = IntGdiCombineRgn(RgnOwn, RgnOwn, RgnTmp, RGN_DIFF);
 
       /* DO NOT Unlock DC while messing with prgnVis! */
@@ -1851,7 +1851,7 @@ NtUserScrollWindowEx(
              RgnWinupd = IntSysCreateRectpRgn( 0, 0, 0, 0);
              IntGdiCombineRgn( RgnWinupd, RgnTemp, 0, RGN_COPY);
           }
-          REGION_iOffsetRgn(RgnTemp, dx, dy);
+          REGION_bOffsetRgn(RgnTemp, dx, dy);
           IntGdiCombineRgn(RgnTemp, RgnTemp, RgnClip, RGN_AND);
           if (hrgnUpdate)
               IntGdiCombineRgn( RgnWinupd, RgnWinupd, RgnTemp, RGN_OR );
diff --git a/reactos/win32ss/user/ntuser/vis.c b/reactos/win32ss/user/ntuser/vis.c
index 2c5dd9a571f..55bbb944996 100644
--- a/reactos/win32ss/user/ntuser/vis.c
+++ b/reactos/win32ss/user/ntuser/vis.c
@@ -81,9 +81,9 @@ VIS_ComputeVisibleRegion(
                   PREGION SiblingClipRgn = RGNOBJAPI_Lock(CurrentSibling->hrgnClip, NULL);
                   if (SiblingClipRgn)
                   {
-                      REGION_iOffsetRgn(ClipRgn, -CurrentSibling->rcWindow.left, -CurrentSibling->rcWindow.top);
+                      REGION_bOffsetRgn(ClipRgn, -CurrentSibling->rcWindow.left, -CurrentSibling->rcWindow.top);
                       IntGdiCombineRgn(ClipRgn, ClipRgn, SiblingClipRgn, RGN_AND);
-                      REGION_iOffsetRgn(ClipRgn, CurrentSibling->rcWindow.left, CurrentSibling->rcWindow.top);
+                      REGION_bOffsetRgn(ClipRgn, CurrentSibling->rcWindow.left, CurrentSibling->rcWindow.top);
                       RGNOBJAPI_Unlock(SiblingClipRgn);
                   }
                }
@@ -113,9 +113,9 @@ VIS_ComputeVisibleRegion(
                PREGION CurrentRgnClip = RGNOBJAPI_Lock(CurrentWindow->hrgnClip, NULL);
                if (CurrentRgnClip)
                {
-                   REGION_iOffsetRgn(ClipRgn, -CurrentWindow->rcWindow.left, -CurrentWindow->rcWindow.top);
+                   REGION_bOffsetRgn(ClipRgn, -CurrentWindow->rcWindow.left, -CurrentWindow->rcWindow.top);
                    IntGdiCombineRgn(ClipRgn, ClipRgn, CurrentRgnClip, RGN_AND);
-                   REGION_iOffsetRgn(ClipRgn, CurrentWindow->rcWindow.left, CurrentWindow->rcWindow.top);
+                   REGION_bOffsetRgn(ClipRgn, CurrentWindow->rcWindow.left, CurrentWindow->rcWindow.top);
                    RGNOBJAPI_Unlock(CurrentRgnClip);
                }
             }
@@ -131,9 +131,9 @@ VIS_ComputeVisibleRegion(
       PREGION WndRgnClip = RGNOBJAPI_Lock(Wnd->hrgnClip, NULL);
       if (WndRgnClip)
       {
-          REGION_iOffsetRgn(VisRgn, -Wnd->rcWindow.left, -Wnd->rcWindow.top);
+          REGION_bOffsetRgn(VisRgn, -Wnd->rcWindow.left, -Wnd->rcWindow.top);
           IntGdiCombineRgn(VisRgn, VisRgn, WndRgnClip, RGN_AND);
-          REGION_iOffsetRgn(VisRgn, Wnd->rcWindow.left, Wnd->rcWindow.top);
+          REGION_bOffsetRgn(VisRgn, Wnd->rcWindow.left, Wnd->rcWindow.top);
           RGNOBJAPI_Unlock(WndRgnClip);
       }
    }
@@ -160,7 +160,7 @@ co_VIS_WindowLayoutChanged(
            return;
 
        IntGdiCombineRgn(TempRgn, NewlyExposed, NULL, RGN_COPY);
-       REGION_iOffsetRgn(TempRgn,
+       REGION_bOffsetRgn(TempRgn,
                          Wnd->rcWindow.left - Parent->rcClient.left,
                          Wnd->rcWindow.top - Parent->rcClient.top);
 
diff --git a/reactos/win32ss/user/ntuser/windc.c b/reactos/win32ss/user/ntuser/windc.c
index 9fc083aa6b1..4935189e51e 100644
--- a/reactos/win32ss/user/ntuser/windc.c
+++ b/reactos/win32ss/user/ntuser/windc.c
@@ -873,7 +873,7 @@ DceResetActiveDCEs(PWND Window)
 
             if (NULL != dc->dclevel.prgnClip)
             {
-               REGION_iOffsetRgn(dc->dclevel.prgnClip, DeltaX, DeltaY);
+               REGION_bOffsetRgn(dc->dclevel.prgnClip, DeltaX, DeltaY);
                dc->fs |= DC_FLAG_DIRTY_RAO;
             }
             if (NULL != pDCE->hrgnClip)
diff --git a/reactos/win32ss/user/ntuser/winpos.c b/reactos/win32ss/user/ntuser/winpos.c
index a80347e7296..3e780417a30 100644
--- a/reactos/win32ss/user/ntuser/winpos.c
+++ b/reactos/win32ss/user/ntuser/winpos.c
@@ -1762,7 +1762,7 @@ co_WinPosSetWindowPos(
          }
          else if(VisBefore)
          {
-            REGION_iOffsetRgn(VisBefore, -Window->rcWindow.left, -Window->rcWindow.top);
+            REGION_bOffsetRgn(VisBefore, -Window->rcWindow.left, -Window->rcWindow.top);
          }
 
          /* Calculate the non client area for resizes, as this is used in the copy region */
@@ -1779,7 +1779,7 @@ co_WinPosSetWindowPos(
              }
              else if(VisBeforeJustClient)
              {
-                 REGION_iOffsetRgn(VisBeforeJustClient, -Window->rcWindow.left, -Window->rcWindow.top);
+                 REGION_bOffsetRgn(VisBeforeJustClient, -Window->rcWindow.left, -Window->rcWindow.top);
              }
          }
       }
@@ -1864,7 +1864,7 @@ co_WinPosSetWindowPos(
       }
       else if(VisAfter)
       {
-         REGION_iOffsetRgn(VisAfter, -Window->rcWindow.left, -Window->rcWindow.top);
+         REGION_bOffsetRgn(VisAfter, -Window->rcWindow.left, -Window->rcWindow.top);
       }
 
       /*
@@ -1905,9 +1905,9 @@ co_WinPosSetWindowPos(
             PREGION RgnUpdate = RGNOBJAPI_Lock(Window->hrgnUpdate, NULL);
             if (RgnUpdate)
             {
-                REGION_iOffsetRgn(CopyRgn, NewWindowRect.left, NewWindowRect.top);
+                REGION_bOffsetRgn(CopyRgn, NewWindowRect.left, NewWindowRect.top);
                 IntGdiCombineRgn(CopyRgn, CopyRgn, RgnUpdate, RGN_DIFF);
-                REGION_iOffsetRgn(CopyRgn, -NewWindowRect.left, -NewWindowRect.top);
+                REGION_bOffsetRgn(CopyRgn, -NewWindowRect.left, -NewWindowRect.top);
                 RGNOBJAPI_Unlock(RgnUpdate);
             }
          }
@@ -1939,7 +1939,7 @@ co_WinPosSetWindowPos(
            * to create a copy of CopyRgn and pass that. We need CopyRgn later
            */
             IntGdiCombineRgn(DcRgnObj, CopyRgn, NULL, RGN_COPY);
-            REGION_iOffsetRgn(DcRgnObj, NewWindowRect.left, NewWindowRect.top);
+            REGION_bOffsetRgn(DcRgnObj, NewWindowRect.left, NewWindowRect.top);
             RGNOBJAPI_Unlock(DcRgnObj);
             Dc = UserGetDCEx( Window,
                               DcRgn,
@@ -1992,7 +1992,7 @@ co_WinPosSetWindowPos(
 
                 PWND Parent = Window->spwndParent;
 
-                REGION_iOffsetRgn( DirtyRgn,
+                REGION_bOffsetRgn( DirtyRgn,
                                 Window->rcWindow.left,
                                 Window->rcWindow.top);
                 if ( (Window->style & WS_CHILD) &&
@@ -2027,7 +2027,7 @@ co_WinPosSetWindowPos(
          if (ExposedRgn)
          {
              RgnType = IntGdiCombineRgn(ExposedRgn, VisBefore, NULL, RGN_COPY);
-             REGION_iOffsetRgn(ExposedRgn,
+             REGION_bOffsetRgn(ExposedRgn,
                                OldWindowRect.left - NewWindowRect.left,
                                OldWindowRect.top  - NewWindowRect.top);