diff --git a/reactos/dll/win32/gdi32/objects/coord.c b/reactos/dll/win32/gdi32/objects/coord.c
index 2050b023c0e..c56791c3932 100644
--- a/reactos/dll/win32/gdi32/objects/coord.c
+++ b/reactos/dll/win32/gdi32/objects/coord.c
@@ -327,7 +327,6 @@ SetViewportExtEx(HDC hdc,
                  int nYExtent,
                  LPSIZE lpSize)
 {
-#if 0
   PDC_ATTR Dc_Attr;
 #if 0
   if (GDI_HANDLE_GET_TYPE(hdc) != GDI_OBJECT_TYPE_DC)
@@ -349,20 +348,23 @@ SetViewportExtEx(HDC hdc,
     }
   }
 #endif
-  if (!GdiGetHandleUserData((HGDIOBJ) hdc, GDI_OBJECT_TYPE_DC, (PVOID) &Dc_Attr)) return FALSE;
+  if (!GdiGetHandleUserData((HGDIOBJ) hdc, GDI_OBJECT_TYPE_DC, (PVOID) &Dc_Attr))
+  {
+      return FALSE;
+  }
 
   if (lpSize)
   {
-     lpSize->cx = Dc_Attr->szlWindowExt.cx;
-     lpSize->cy = Dc_Attr->szlWindowExt.cy;
+     lpSize->cx = Dc_Attr->szlViewportExt.cx;
+     lpSize->cy = Dc_Attr->szlViewportExt.cy;
   }
 
-  if ((Dc_Attr->ptlWindowExt.cx == nXExtent) && (Dc_Attr->ptlWindowExt.cy == nYExtent))
+  if ((Dc_Attr->szlViewportExt.cx == nXExtent) && (Dc_Attr->szlViewportExt.cy == nYExtent))
      return TRUE;
 
-  if ((Dc_Attr->iMapMode == MM_ISOTROPIC) && (Dc_Attr->iMapMode == MM_ANISOTROPIC))
+  if ((Dc_Attr->iMapMode == MM_ISOTROPIC) || (Dc_Attr->iMapMode == MM_ANISOTROPIC))
   {
-     if (NtCurrentTeb()->GdiTebBatch.HDC == (ULONG)hdc)
+     if (NtCurrentTeb()->GdiTebBatch.HDC == hdc)
      {
         if (Dc_Attr->ulDirty_ & DC_FONTTEXT_DIRTY)
         {
@@ -370,14 +372,12 @@ SetViewportExtEx(HDC hdc,
            Dc_Attr->ulDirty_ &= ~(DC_MODE_DIRTY|DC_FONTTEXT_DIRTY);
         }
      }
-     Dc_Attr->szlWindowExt.cx = nXExtent;
-     Dc_Attr->szlWindowExt.cy = nYExtent;
+     Dc_Attr->szlViewportExt.cx = nXExtent;
+     Dc_Attr->szlViewportExt.cy = nYExtent;
      if (Dc_Attr->dwLayout & LAYOUT_RTL) NtGdiMirrorWindowOrg(hdc);
      Dc_Attr->flXform |= (PAGE_EXTENTS_CHANGED|INVALIDATE_ATTRIBUTES|DEVICE_TO_WORLD_INVALID);
   }
   return TRUE;
-#endif
-  return NtGdiSetViewportExtEx(hdc, nXExtent, nYExtent, lpSize);
 }
 
 /*
@@ -452,7 +452,6 @@ SetWindowExtEx(HDC hdc,
                int nYExtent,
                LPSIZE lpSize)
 {
-#if 0
   PDC_ATTR Dc_Attr;
 #if 0
   if (GDI_HANDLE_GET_TYPE(hdc) != GDI_OBJECT_TYPE_DC)
@@ -488,14 +487,14 @@ SetWindowExtEx(HDC hdc,
      NtGdiMirrorWindowOrg(hdc);
      Dc_Attr->flXform |= (PAGE_EXTENTS_CHANGED|INVALIDATE_ATTRIBUTES|DEVICE_TO_WORLD_INVALID);
   }
-  else if ((Dc_Attr->iMapMode == MM_ISOTROPIC) && (Dc_Attr->iMapMode == MM_ANISOTROPIC))
+  else if ((Dc_Attr->iMapMode == MM_ISOTROPIC) || (Dc_Attr->iMapMode == MM_ANISOTROPIC))
   {
      if ((Dc_Attr->szlWindowExt.cx == nXExtent) && (Dc_Attr->szlWindowExt.cy == nYExtent))
         return TRUE;
 
-     if ((!nXExtent) && (!nYExtent)) return FALSE;
+     if ((!nXExtent) || (!nYExtent)) return FALSE;
 
-     if (NtCurrentTeb()->GdiTebBatch.HDC == (ULONG)hdc)
+     if (NtCurrentTeb()->GdiTebBatch.HDC == hdc)
      {
         if (Dc_Attr->ulDirty_ & DC_FONTTEXT_DIRTY)
         {
@@ -509,8 +508,6 @@ SetWindowExtEx(HDC hdc,
      Dc_Attr->flXform |= (PAGE_EXTENTS_CHANGED|INVALIDATE_ATTRIBUTES|DEVICE_TO_WORLD_INVALID);  
   }
   return TRUE; // Return TRUE.
-#endif
-  return NtGdiSetWindowExtEx(hdc, nXExtent, nYExtent, lpSize);
 }
 
 /*
diff --git a/reactos/include/reactos/win32k/ntgdibad.h b/reactos/include/reactos/win32k/ntgdibad.h
index 8b43f46cb8f..3bbc3338c7e 100644
--- a/reactos/include/reactos/win32k/ntgdibad.h
+++ b/reactos/include/reactos/win32k/ntgdibad.h
@@ -91,16 +91,6 @@ NtGdiOffsetWindowOrgEx (
 	LPPOINT	Point
 	);
 
-/* Needs to be done in user-mode. */
-BOOL
-APIENTRY
-NtGdiSetWindowExtEx (
-	HDC	hDC,
-	int	XExtent,
-	int	YExtent,
-	LPSIZE	Size
-	);
-
 /* Needs to be done in user-mode. */
 BOOL
 APIENTRY
@@ -111,16 +101,6 @@ NtGdiSetViewportOrgEx (
 	LPPOINT	Point
 	);
 
-/* Needs to be done in user-mode. */
-BOOL
-APIENTRY
-NtGdiSetViewportExtEx (
-	HDC	hDC,
-	int	XExtent,
-	int	YExtent,
-	LPSIZE	Size
-	);
-
 /* Needs to be done in user-mode. */
 BOOL
 APIENTRY
diff --git a/reactos/subsystems/win32/win32k/include/coord.h b/reactos/subsystems/win32/win32k/include/coord.h
index e518102a9e1..418e623fa8f 100644
--- a/reactos/subsystems/win32/win32k/include/coord.h
+++ b/reactos/subsystems/win32/win32k/include/coord.h
@@ -23,5 +23,6 @@ IntGdiModifyWorldTransform(PDC pDc,
                            DWORD Mode);
 
 VOID FASTCALL IntMirrorWindowOrg(PDC);
+void FASTCALL IntFixIsotropicMapping(PDC dc);
 
 #endif
diff --git a/reactos/subsystems/win32/win32k/objects/coord.c b/reactos/subsystems/win32/win32k/objects/coord.c
index ff4b216d04a..1a1c9261391 100644
--- a/reactos/subsystems/win32/win32k/objects/coord.c
+++ b/reactos/subsystems/win32/win32k/objects/coord.c
@@ -37,29 +37,33 @@
 void FASTCALL
 IntFixIsotropicMapping(PDC dc)
 {
-    ULONG xdim;
-    ULONG ydim;
-    PDC_ATTR Dc_Attr = dc->pDc_Attr;
-    if (!Dc_Attr) Dc_Attr = &dc->Dc_Attr;
+    PDC_ATTR pDcAttr;
+    LONG fx, fy, s;
 
-    xdim = EngMulDiv(Dc_Attr->szlViewportExt.cx,
-                     ((PGDIDEVICE)dc->pPDev)->GDIInfo.ulHorzSize,
-                     ((PGDIDEVICE)dc->pPDev)->GDIInfo.ulHorzRes) /
-                                         Dc_Attr->szlWindowExt.cx;
-    ydim = EngMulDiv(Dc_Attr->szlViewportExt.cy,
-                     ((PGDIDEVICE)dc->pPDev)->GDIInfo.ulVertSize,
-                     ((PGDIDEVICE)dc->pPDev)->GDIInfo.ulVertRes) /
-                                         Dc_Attr->szlWindowExt.cy;
+    /* Get a pointer to the DC_ATTR */
+    pDcAttr = dc->pDc_Attr;
+    if (!pDcAttr) pDcAttr = &dc->Dc_Attr;
 
-    if (xdim > ydim)
+    /* Check if all values are valid */
+    if (pDcAttr->szlWindowExt.cx == 0 || pDcAttr->szlWindowExt.cy == 0 ||
+        pDcAttr->szlViewportExt.cx == 0 || pDcAttr->szlViewportExt.cy == 0)
     {
-        Dc_Attr->szlViewportExt.cx = Dc_Attr->szlViewportExt.cx * abs(ydim / xdim);
-        if (!Dc_Attr->szlViewportExt.cx) Dc_Attr->szlViewportExt.cx = 1;
+        /* Don't recalculate */
+        return;
     }
-    else
+
+    fx = abs(pDcAttr->szlWindowExt.cx * pDcAttr->szlViewportExt.cy);
+    fy = abs(pDcAttr->szlWindowExt.cy * pDcAttr->szlViewportExt.cx);
+
+    if (fy > fx)
     {
-        Dc_Attr->szlViewportExt.cy = Dc_Attr->szlViewportExt.cy * abs(xdim / ydim);
-        if (!Dc_Attr->szlViewportExt.cy) Dc_Attr->szlViewportExt.cy = 1;
+        s = pDcAttr->szlWindowExt.cy * pDcAttr->szlViewportExt.cx > 0 ? 1 : -1;
+        pDcAttr->szlViewportExt.cx = s * fx / pDcAttr->szlWindowExt.cy;
+    }
+    else if (fx > fy)
+    {
+        s = pDcAttr->szlWindowExt.cx * pDcAttr->szlViewportExt.cy > 0 ? 1 : -1;
+        pDcAttr->szlViewportExt.cy = s * fy / pDcAttr->szlWindowExt.cx;
     }
 }
 
@@ -716,78 +720,6 @@ IntGdiSetMapMode(PDC  dc,
     return PrevMapMode;
 }
 
-BOOL
-APIENTRY
-NtGdiSetViewportExtEx(HDC  hDC,
-                      int  XExtent,
-                      int  YExtent,
-                      LPSIZE  Size)
-{
-    PDC dc;
-    PDC_ATTR Dc_Attr;
-
-    dc = DC_LockDc(hDC);
-    if (!dc)
-    {
-        SetLastWin32Error(ERROR_INVALID_HANDLE);
-        return FALSE;
-    }
-    Dc_Attr = dc->pDc_Attr;
-    if (!Dc_Attr) Dc_Attr = &dc->Dc_Attr;
-
-    switch (Dc_Attr->iMapMode)
-    {
-        case MM_HIENGLISH:
-        case MM_HIMETRIC:
-        case MM_LOENGLISH:
-        case MM_LOMETRIC:
-        case MM_TEXT:
-        case MM_TWIPS:
-            DC_UnlockDc(dc);
-            return FALSE;
-
-        case MM_ISOTROPIC:
-            // Here we should (probably) check that SetWindowExtEx *really* has
-            // been called
-            break;
-    }
-
-    if (Size)
-    {
-        NTSTATUS Status = STATUS_SUCCESS;
-
-        _SEH2_TRY
-        {
-            ProbeForWrite(Size, sizeof(SIZE), 1);
-            Size->cx = Dc_Attr->szlViewportExt.cx;
-            Size->cy = Dc_Attr->szlViewportExt.cy;
-
-            Dc_Attr->szlViewportExt.cx = XExtent;
-            Dc_Attr->szlViewportExt.cy = YExtent;
-
-            if (Dc_Attr->iMapMode == MM_ISOTROPIC)
-                IntFixIsotropicMapping(dc);
-        }
-        _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
-        {
-            Status = _SEH2_GetExceptionCode();
-        }
-        _SEH2_END;
-
-        if (!NT_SUCCESS(Status))
-        {
-            SetLastNtError(Status);
-            DC_UnlockDc(dc);
-            return FALSE;
-        }
-    }
-
-
-    DC_UpdateXforms(dc);
-    DC_UnlockDc(dc);
-
-    return TRUE;
-}
 
 BOOL
 APIENTRY
@@ -841,70 +773,6 @@ NtGdiSetViewportOrgEx(HDC  hDC,
     return TRUE;
 }
 
-BOOL
-APIENTRY
-NtGdiSetWindowExtEx(HDC  hDC,
-                    int  XExtent,
-                    int  YExtent,
-                    LPSIZE  Size)
-{
-    PDC dc;
-    PDC_ATTR Dc_Attr;
-
-    dc = DC_LockDc(hDC);
-    if (!dc)
-    {
-        SetLastWin32Error(ERROR_INVALID_HANDLE);
-        return FALSE;
-    }
-    Dc_Attr = dc->pDc_Attr;
-    if (!Dc_Attr) Dc_Attr = &dc->Dc_Attr;
-
-    switch (Dc_Attr->iMapMode)
-    {
-        case MM_HIENGLISH:
-        case MM_HIMETRIC:
-        case MM_LOENGLISH:
-        case MM_LOMETRIC:
-        case MM_TEXT:
-        case MM_TWIPS:
-            DC_UnlockDc(dc);
-            return FALSE;
-    }
-
-    if (Size)
-    {
-        NTSTATUS Status = STATUS_SUCCESS;
-
-        _SEH2_TRY
-        {
-            ProbeForWrite(Size, sizeof(SIZE), 1);
-            Size->cx = Dc_Attr->szlWindowExt.cx;
-            Size->cy = Dc_Attr->szlWindowExt.cy;
-        }
-        _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
-        {
-            Status = _SEH2_GetExceptionCode();
-        }
-        _SEH2_END;
-
-        if (!NT_SUCCESS(Status))
-        {
-            SetLastNtError(Status);
-            DC_UnlockDc(dc);
-            return FALSE;
-        }
-    }
-
-    Dc_Attr->szlWindowExt.cx = XExtent;
-    Dc_Attr->szlWindowExt.cy = YExtent;
-
-    DC_UpdateXforms(dc);
-    DC_UnlockDc(dc);
-
-    return TRUE;
-}
-
 BOOL
 APIENTRY
 NtGdiSetWindowOrgEx(HDC  hDC,
diff --git a/reactos/subsystems/win32/win32k/objects/dc.c b/reactos/subsystems/win32/win32k/objects/dc.c
index 0a54a783ec4..ce67fb23d4e 100644
--- a/reactos/subsystems/win32/win32k/objects/dc.c
+++ b/reactos/subsystems/win32/win32k/objects/dc.c
@@ -65,7 +65,6 @@ NtGdiCreateCompatibleDC(HDC hDC)
   UNICODE_STRING DriverName;
   DWORD Layout = 0;
 
-  DisplayDC = NULL;
   if (hDC == NULL)
     {
       RtlInitUnicodeString(&DriverName, L"DISPLAY");
@@ -1266,6 +1265,33 @@ IntGetAspectRatioFilter(PDC pDC,
   return TRUE;
 }
 
+VOID
+FASTCALL
+IntGetViewportExtEx(PDC pdc, LPSIZE pSize)
+{
+    PDC_ATTR pDc_Attr;
+
+    /* Get a pointer to the dc attribute */
+    pDc_Attr = pdc->pDc_Attr;
+    if (!pDc_Attr) pDc_Attr = &pdc->Dc_Attr;
+
+    /* Check if we need to recalculate */
+    if (pDc_Attr->flXform & PAGE_EXTENTS_CHANGED)
+    {
+        /* Check if we need to do isotropic fixup */
+        if (pDc_Attr->iMapMode == MM_ISOTROPIC)
+        {
+            IntFixIsotropicMapping(pdc);
+        }
+
+        /* Update xforms, CHECKME: really done here? */
+        DC_UpdateXforms(pdc);
+    }
+
+    /* Copy the viewport extension */
+    *pSize = pDc_Attr->szlViewportExt;
+}
+
 BOOL APIENTRY
 NtGdiGetDCPoint( HDC hDC, UINT iPoint, PPOINTL Point)
 {
diff --git a/reactos/subsystems/win32/win32k/objects/dcutil.c b/reactos/subsystems/win32/win32k/objects/dcutil.c
index 881d7a8bac0..19c53bfb5ef 100644
--- a/reactos/subsystems/win32/win32k/objects/dcutil.c
+++ b/reactos/subsystems/win32/win32k/objects/dcutil.c
@@ -170,7 +170,6 @@ DC_GET_VAL( INT, IntGdiGetStretchBltMode, jStretchBltMode )
 DC_GET_VAL( UINT, IntGdiGetTextAlign, lTextAlign )
 DC_GET_VAL( COLORREF, IntGdiGetTextColor, crForegroundClr )
 
-DC_GET_VAL_EX( GetViewportExtEx, szlViewportExt.cx, szlViewportExt.cy, SIZE, cx, cy )
 DC_GET_VAL_EX( GetViewportOrgEx, ptlViewportOrg.x, ptlViewportOrg.y, POINT, x, y )
 DC_GET_VAL_EX( GetWindowExtEx, szlWindowExt.cx, szlWindowExt.cy, SIZE, cx, cy )
 DC_GET_VAL_EX( GetWindowOrgEx, ptlWindowOrg.x, ptlWindowOrg.y, POINT, x, y )
diff --git a/reactos/subsystems/win32/win32k/w32ksvc.db b/reactos/subsystems/win32/win32k/w32ksvc.db
index bedb28e2cc8..3a8e5e71f94 100644
--- a/reactos/subsystems/win32/win32k/w32ksvc.db
+++ b/reactos/subsystems/win32/win32k/w32ksvc.db
@@ -675,9 +675,7 @@ NtGdiDrawStream                                  3
 #
 #ReactOS specific syscalls
 NtGdiSetDIBits                          7
-NtGdiSetViewportExtEx                   4
 NtGdiSetViewportOrgEx                   4
-NtGdiSetWindowExtEx                     4
 NtGdiSetWindowOrgEx                     4
 NtGdiGetFontFamilyInfo                  4
 NtGdiOffsetViewportOrgEx                4