--- a/modules/libpr0n/src/imgFrame.cpp
+++ b/modules/libpr0n/src/imgFrame.cpp
@@ -848,16 +848,21 @@ nsresult imgFrame::LockImageData()
 #endif
   }
 
   // We might write to the bits in this image surface, so we need to make the
   // surface ready for that.
   if (mImageSurface)
     mImageSurface->Flush();
 
+#ifdef USE_WIN_SURFACE
+  if (mWinSurface)
+    mWinSurface->Flush();
+#endif
+
   return NS_OK;
 }
 
 nsresult imgFrame::UnlockImageData()
 {
   if (mPalettedImageData)
     return NS_ERROR_NOT_AVAILABLE;
 
@@ -867,16 +872,21 @@ nsresult imgFrame::UnlockImageData()
   }
 
   mLocked = PR_FALSE;
 
   // Assume we've been written to.
   if (mImageSurface)
     mImageSurface->MarkDirty();
 
+#ifdef USE_WIN_SURFACE
+  if (mWinSurface)
+    mWinSurface->MarkDirty();
+#endif
+
 #ifdef XP_MACOSX
   // The quartz image surface (ab)uses the flush method to get the
   // cairo_image_surface data into a CGImage, so we have to call Flush() here.
   if (mQuartzSurface)
     mQuartzSurface->Flush();
 #endif
   return NS_OK;
 }