diff --git a/gfx/src/mac/nsImageMac.cpp b/gfx/src/mac/nsImageMac.cpp
index afefabb93cea..daf1d6f376d2 100644
--- a/gfx/src/mac/nsImageMac.cpp
+++ b/gfx/src/mac/nsImageMac.cpp
@@ -370,7 +370,7 @@ NS_IMETHODIMP nsImageMac::Draw(nsIRenderingContext &aContext, nsDrawingSurface a
     CopyBitsWithMask((BitMap*)(&mImagePixmap),
         mMaskBitsHandle ? (BitMap*)(&mMaskPixmap) : nsnull, mAlphaDepth,
         (BitMap*)(*destPixels),
-        srcRect, maskRect, dstRect);
+        srcRect, maskRect, dstRect, PR_TRUE);
 	}
 	
 	return NS_OK;
@@ -428,7 +428,7 @@ NS_IMETHODIMP nsImageMac :: DrawToImage(nsIImage* aDstImage, PRInt32 aDX, PRInt3
 
   CopyBitsWithMask((BitMap*)(&mImagePixmap),
       mMaskBitsHandle ? (BitMap*)(&mMaskPixmap) : nsnull, mAlphaDepth,
-      (BitMap*)(destPixels), srcRect, maskRect, dstRect);
+      (BitMap*)(destPixels), srcRect, maskRect, dstRect, PR_FALSE);
   
   aDstImage->UnlockImagePixels(PR_FALSE);
   aDstImage->UnlockImagePixels(PR_TRUE);
@@ -822,15 +822,20 @@ OSErr nsImageMac::AllocateGWorld(PRInt16 depth, CTabHandle colorTable, const Rec
 }
 
 void nsImageMac::CopyBitsWithMask(const BitMap* srcBits, const BitMap* maskBits, PRInt16 maskDepth, const BitMap* destBits,
-        const Rect& srcRect, const Rect& maskRect, const Rect& destRect)
+        const Rect& srcRect, const Rect& maskRect, const Rect& destRect, PRBool inDrawingToPort)
 {
   if (maskBits)
   {
-    // we need to pass in the clip region, even if it doesn't intersect the image, to avoid a bug
-    // on Mac OS X that causes bad image drawing (see bug 137295).
     StRegionFromPool    clipRegion;
-    ::GetClip(clipRegion);
-    ::CopyDeepMask(srcBits, maskBits, destBits, &srcRect, &maskRect, &destRect, srcCopy, clipRegion);
+    
+    if (inDrawingToPort)
+    {
+      // we need to pass in the clip region, even if it doesn't intersect the image, to avoid a bug
+      // on Mac OS X that causes bad image drawing (see bug 137295).
+      ::GetClip(clipRegion);
+    }
+    
+    ::CopyDeepMask(srcBits, maskBits, destBits, &srcRect, &maskRect, &destRect, srcCopy, inDrawingToPort ? clipRegion : nsnull);
   }
   else
   {
@@ -889,7 +894,7 @@ nsImageMac :: ConvertToPICT ( PicHandle* outPicture )
   		// copy from the destination into our temp GWorld, to get the background
       CopyBitsWithMask((BitMap*)(&mImagePixmap),
           mMaskBitsHandle ? (BitMap*)(&mMaskPixmap) : nsnull, mAlphaDepth,
-          (BitMap*)(*tempPixMap), picFrame, maskFrame, picFrame);
+          (BitMap*)(*tempPixMap), picFrame, maskFrame, picFrame, PR_FALSE);
       
   		// now copy into the picture
   		GWorldPtr currPort;
@@ -993,7 +998,7 @@ nsImageMac::ConvertToIcon(  const nsRect& aSrcRegion,
     }
     
     //returns null if there size specified isn't a valid size for an icon
-    OSType iconType = MakeIconType(aIconSize, aIconDepth, false);
+    OSType iconType = MakeIconType(aIconSize, aIconDepth, PR_FALSE);
     if (iconType == nil) {
         return NS_ERROR_INVALID_ARG;
     } 
@@ -1080,7 +1085,7 @@ nsImageMac::ConvertAlphaToIconMask(  const nsRect& aSrcRegion,
     *aOutIconType = nsnull;
     
     //returns null if there size specified isn't a valid size for an icon
-    OSType iconType = MakeIconType(aMaskSize, aMaskDepth, true);
+    OSType iconType = MakeIconType(aMaskSize, aMaskDepth, PR_TRUE);
     if (iconType == nil) {
         return NS_ERROR_INVALID_ARG;
     } 
@@ -1608,7 +1613,7 @@ nsresult nsImageMac::DrawTileQuickly(nsIRenderingContext &aContext,
 	  		// CopyBits will do the truncation for us at the edges
         CopyBitsWithMask((BitMap*)(&mImagePixmap),
             mMaskBitsHandle ? (BitMap*)(&mMaskPixmap) : nsnull, mAlphaDepth,
-            (BitMap*)(*destPixels), imageRect, imageRect, imageDestRect);
+            (BitMap*)(*destPixels), imageRect, imageRect, imageDestRect, PR_TRUE);
 	  	}
   	}
   
@@ -1791,7 +1796,7 @@ nsresult nsImageMac::DrawTileQuickly(nsIRenderingContext &aContext,
     // finally, copy to the destination
     CopyBitsWithMask((BitMap*)(*tilingPixels),
         maskingPixels ? (BitMap*)(*maskingPixels) : nsnull, mAlphaDepth,
-        (BitMap*)(*destPixels), tileRect, tileRect, tileDestRect);
+        (BitMap*)(*destPixels), tileRect, tileRect, tileDestRect, PR_TRUE);
     
   } // scope for locks
 
diff --git a/gfx/src/mac/nsImageMac.h b/gfx/src/mac/nsImageMac.h
index 7ae0fbfc39fa..6079408b6f9b 100644
--- a/gfx/src/mac/nsImageMac.h
+++ b/gfx/src/mac/nsImageMac.h
@@ -181,7 +181,7 @@ protected:
                                     Handle *aMask);                                                
 	
 	static void       CopyBitsWithMask(const BitMap* srcBits, const BitMap* maskBits, PRInt16 maskDepth, const BitMap* destBits,
-	                          const Rect& srcRect, const Rect& maskRect, const Rect& destRect);
+	                          const Rect& srcRect, const Rect& maskRect, const Rect& destRect, PRBool inDrawingToPort);
 	
 	static PRBool     RenderingToPrinter(nsIRenderingContext &aContext);