diff --git a/accessible/src/base/nsCaretAccessible.cpp b/accessible/src/base/nsCaretAccessible.cpp
index 3aa147e4ddb0..7053f6106bd4 100644
--- a/accessible/src/base/nsCaretAccessible.cpp
+++ b/accessible/src/base/nsCaretAccessible.cpp
@@ -343,7 +343,7 @@ nsCaretAccessible::GetCaretRect(nsIWidget **aOutWidget)
   NS_ENSURE_TRUE(presContext, nsIntRect());
 
   rect += offsetFromWidget;
-  caretRect = nsRect::ToOutsidePixels(rect, presContext->AppUnitsPerDevPixel());
+  caretRect = rect.ToOutsidePixels(presContext->AppUnitsPerDevPixel());
 
   caretRect.MoveBy((*aOutWidget)->WidgetToScreenOffset());
 
diff --git a/content/events/src/nsContentEventHandler.cpp b/content/events/src/nsContentEventHandler.cpp
index 480978d8b0b4..9fa13a29356f 100644
--- a/content/events/src/nsContentEventHandler.cpp
+++ b/content/events/src/nsContentEventHandler.cpp
@@ -595,7 +595,7 @@ nsContentEventHandler::OnQueryTextRect(nsQueryContentEvent* aEvent)
     rect.UnionRect(rect, frameRect);
   }
   aEvent->mReply.mRect =
-      nsRect::ToOutsidePixels(rect, mPresContext->AppUnitsPerDevPixel());
+      rect.ToOutsidePixels(mPresContext->AppUnitsPerDevPixel());
   aEvent->mSucceeded = PR_TRUE;
   return NS_OK;
 }
@@ -624,7 +624,7 @@ nsContentEventHandler::OnQueryEditorRect(nsQueryContentEvent* aEvent)
   }
 
   aEvent->mReply.mRect =
-      nsRect::ToOutsidePixels(resultRect, mPresContext->AppUnitsPerDevPixel());
+      resultRect.ToOutsidePixels(mPresContext->AppUnitsPerDevPixel());
   aEvent->mSucceeded = PR_TRUE;
   return NS_OK;
 }
@@ -658,7 +658,7 @@ nsContentEventHandler::OnQueryCaretRect(nsQueryContentEvent* aEvent)
                                       mSelection, &rect,
                                       &isCollapsed, nsnull);
       aEvent->mReply.mRect =
-          nsRect::ToOutsidePixels(rect, mPresContext->AppUnitsPerDevPixel());
+          rect.ToOutsidePixels(mPresContext->AppUnitsPerDevPixel());
       NS_ENSURE_SUCCESS(rv, rv);
       aEvent->mSucceeded = PR_TRUE;
       return NS_OK;
@@ -690,7 +690,7 @@ nsContentEventHandler::OnQueryCaretRect(nsQueryContentEvent* aEvent)
   NS_ENSURE_SUCCESS(rv, rv);
 
   aEvent->mReply.mRect =
-      nsRect::ToOutsidePixels(rect, mPresContext->AppUnitsPerDevPixel());
+      rect.ToOutsidePixels(mPresContext->AppUnitsPerDevPixel());
   aEvent->mSucceeded = PR_TRUE;
   return NS_OK;
 }
diff --git a/editor/libeditor/base/nsEditor.cpp b/editor/libeditor/base/nsEditor.cpp
index b0615d13f55c..255e093b1d72 100644
--- a/editor/libeditor/base/nsEditor.cpp
+++ b/editor/libeditor/base/nsEditor.cpp
@@ -2001,8 +2001,7 @@ nsEditor::QueryComposition(nsTextEventReply* aReply)
                                     &(aReply->mCursorIsCollapsed),
                                     &view);
       aReply->mCursorPosition =
-        nsRect::ToOutsidePixels(rect,
-                                ps->GetPresContext()->AppUnitsPerDevPixel());
+        rect.ToOutsidePixels(ps->GetPresContext()->AppUnitsPerDevPixel());
       if (NS_SUCCEEDED(result) && view)
         aReply->mReferenceWidget = view->GetWidget();
     }
diff --git a/editor/libeditor/text/nsPlaintextEditor.cpp b/editor/libeditor/text/nsPlaintextEditor.cpp
index b25148e7f70e..7270afad9e60 100644
--- a/editor/libeditor/text/nsPlaintextEditor.cpp
+++ b/editor/libeditor/text/nsPlaintextEditor.cpp
@@ -1735,8 +1735,7 @@ nsPlaintextEditor::SetCompositionString(const nsAString& aCompositionString, nsI
                                          &(aReply->mCursorIsCollapsed),
                                          &view);
     aReply->mCursorPosition =
-       nsRect::ToOutsidePixels(rect,
-                               ps->GetPresContext()->AppUnitsPerDevPixel());
+       rect.ToOutsidePixels(ps->GetPresContext()->AppUnitsPerDevPixel());
     NS_ASSERTION(NS_SUCCEEDED(result), "cannot get caret position");
     if (NS_SUCCEEDED(result) && view)
       aReply->mReferenceWidget = view->GetWidget();
diff --git a/gfx/public/nsRect.h b/gfx/public/nsRect.h
index c903fdfbb395..14fce5d3bf3a 100644
--- a/gfx/public/nsRect.h
+++ b/gfx/public/nsRect.h
@@ -186,9 +186,9 @@ struct NS_GFX nsRect {
   nscoord XMost() const {return x + width;}
   nscoord YMost() const {return y + height;}
 
-  static inline nsIntRect ToNearestPixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
-  static inline nsIntRect ToOutsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
-  static inline nsIntRect ToInsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
+  inline nsIntRect ToNearestPixels(nscoord aAppUnitsPerPixel) const;
+  inline nsIntRect ToOutsidePixels(nscoord aAppUnitsPerPixel) const;
+  inline nsIntRect ToInsidePixels(nscoord aAppUnitsPerPixel) const;
 };
 
 struct NS_GFX nsIntRect {
@@ -305,7 +305,7 @@ struct NS_GFX nsIntRect {
   PRInt32 XMost() const {return x + width;}
   PRInt32 YMost() const {return y + height;}
 
-  static inline nsRect ToAppUnits(const nsIntRect &aRect, nscoord aAppUnitsPerPixel);
+  inline nsRect ToAppUnits(nscoord aAppUnitsPerPixel) const;
 };
 
 /*
@@ -313,54 +313,54 @@ struct NS_GFX nsIntRect {
  */
 // scale the rect but round to preserve centers
 inline nsIntRect
-nsRect::ToNearestPixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+nsRect::ToNearestPixels(nscoord aAppUnitsPerPixel) const
 {
   nsIntRect rect;
-  rect.x = NSToIntRound(NSAppUnitsToFloatPixels(aRect.x, float(aAppUnitsPerPixel)));
-  rect.y = NSToIntRound(NSAppUnitsToFloatPixels(aRect.y, float(aAppUnitsPerPixel)));
-  rect.width  = NSToIntRound(NSAppUnitsToFloatPixels(aRect.XMost(),
+  rect.x = NSToIntRound(NSAppUnitsToFloatPixels(x, float(aAppUnitsPerPixel)));
+  rect.y = NSToIntRound(NSAppUnitsToFloatPixels(y, float(aAppUnitsPerPixel)));
+  rect.width  = NSToIntRound(NSAppUnitsToFloatPixels(XMost(),
                              float(aAppUnitsPerPixel))) - rect.x;
-  rect.height = NSToIntRound(NSAppUnitsToFloatPixels(aRect.YMost(),
+  rect.height = NSToIntRound(NSAppUnitsToFloatPixels(YMost(),
                              float(aAppUnitsPerPixel))) - rect.y;
   return rect;
 }
 
 // scale the rect but round to smallest containing rect
 inline nsIntRect
-nsRect::ToOutsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+nsRect::ToOutsidePixels(nscoord aAppUnitsPerPixel) const
 {
   nsIntRect rect;
-  rect.x = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.x, float(aAppUnitsPerPixel)));
-  rect.y = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.y, float(aAppUnitsPerPixel)));
-  rect.width  = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.XMost(),
+  rect.x = NSToIntFloor(NSAppUnitsToFloatPixels(x, float(aAppUnitsPerPixel)));
+  rect.y = NSToIntFloor(NSAppUnitsToFloatPixels(y, float(aAppUnitsPerPixel)));
+  rect.width  = NSToIntCeil(NSAppUnitsToFloatPixels(XMost(),
                             float(aAppUnitsPerPixel))) - rect.x;
-  rect.height = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.YMost(),
+  rect.height = NSToIntCeil(NSAppUnitsToFloatPixels(YMost(),
                             float(aAppUnitsPerPixel))) - rect.y;
   return rect;
 }
 
 // scale the rect but round to largest contained rect
 inline nsIntRect
-nsRect::ToInsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+nsRect::ToInsidePixels(nscoord aAppUnitsPerPixel) const
 {
   nsIntRect rect;
-  rect.x = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.x, float(aAppUnitsPerPixel)));
-  rect.y = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.y, float(aAppUnitsPerPixel)));
-  rect.width  = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.XMost(),
+  rect.x = NSToIntCeil(NSAppUnitsToFloatPixels(x, float(aAppUnitsPerPixel)));
+  rect.y = NSToIntCeil(NSAppUnitsToFloatPixels(y, float(aAppUnitsPerPixel)));
+  rect.width  = NSToIntFloor(NSAppUnitsToFloatPixels(XMost(),
                              float(aAppUnitsPerPixel))) - rect.x;
-  rect.height = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.YMost(),
+  rect.height = NSToIntFloor(NSAppUnitsToFloatPixels(YMost(),
                              float(aAppUnitsPerPixel))) - rect.y;
   return rect;
 }
 
 // app units are integer multiples of pixels, so no rounding needed
 inline nsRect
-nsIntRect::ToAppUnits(const nsIntRect &aRect, nscoord aAppUnitsPerPixel)
+nsIntRect::ToAppUnits(nscoord aAppUnitsPerPixel) const
 {
-  return nsRect(NSIntPixelsToAppUnits(aRect.x, aAppUnitsPerPixel),
-                NSIntPixelsToAppUnits(aRect.y, aAppUnitsPerPixel),
-                NSIntPixelsToAppUnits(aRect.width, aAppUnitsPerPixel),
-                NSIntPixelsToAppUnits(aRect.height, aAppUnitsPerPixel));
+  return nsRect(NSIntPixelsToAppUnits(x, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(y, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(width, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(height, aAppUnitsPerPixel));
 }
 
 #ifdef DEBUG
diff --git a/layout/base/nsImageLoader.cpp b/layout/base/nsImageLoader.cpp
index 994ae66175cc..249082094cb1 100644
--- a/layout/base/nsImageLoader.cpp
+++ b/layout/base/nsImageLoader.cpp
@@ -193,7 +193,7 @@ NS_IMETHODIMP nsImageLoader::FrameChanged(imgIContainer *aContainer,
     return NS_OK;
   }
   
-  nsRect r = nsIntRect::ToAppUnits(*dirtyRect, nsPresContext::AppUnitsPerCSSPixel());
+  nsRect r = dirtyRect->ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
 
   RedrawDirtyFrame(&r);
 
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 3eeb0036f445..219f892fa8b3 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -5407,7 +5407,7 @@ PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
   nsIDeviceContext* deviceContext = pc->DeviceContext();
 
   // use the rectangle to create the surface
-  nsIntRect pixelArea = nsRect::ToOutsidePixels(aArea, pc->AppUnitsPerDevPixel());
+  nsIntRect pixelArea = aArea.ToOutsidePixels(pc->AppUnitsPerDevPixel());
 
   // if the area of the image is larger than the maximum area, scale it down
   float scale = 0.0;
@@ -5541,7 +5541,7 @@ PresShell::RenderNode(nsIDOMNode* aNode,
     aRegion->GetBoundingBox(&rrectPixels.x, &rrectPixels.y,
                             &rrectPixels.width, &rrectPixels.height);
 
-    nsRect rrect = nsIntRect::ToAppUnits(rrectPixels, nsPresContext::AppUnitsPerCSSPixel());
+    nsRect rrect = rrectPixels.ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
     area.IntersectRect(area, rrect);
     
     nsPresContext* pc = GetPresContext();
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 4e9c3f02a0e4..936766a43379 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -870,7 +870,7 @@ void nsDisplaySelectionOverlay::Paint(nsDisplayListBuilder* aBuilder,
 
   nsRect rect(aBuilder->ToReferenceFrame(mFrame), mFrame->GetSize());
   rect.IntersectRect(rect, aDirtyRect);
-  nsIntRect pxRect = nsRect::ToOutsidePixels(rect, mFrame->PresContext()->AppUnitsPerDevPixel());
+  nsIntRect pxRect = rect.ToOutsidePixels(mFrame->PresContext()->AppUnitsPerDevPixel());
   ctx->NewPath();
   ctx->Rectangle(gfxRect(pxRect.x, pxRect.y, pxRect.width, pxRect.height), PR_TRUE);
   ctx->Fill();
@@ -3608,7 +3608,7 @@ nsIntRect nsIFrame::GetScreenRectExternal() const
 
 nsIntRect nsIFrame::GetScreenRect() const
 {
-  return nsRect::ToNearestPixels(GetScreenRectInAppUnits(), PresContext()->AppUnitsPerDevPixel());
+  return GetScreenRectInAppUnits().ToNearestPixels(PresContext()->AppUnitsPerDevPixel());
 }
 
 // virtual
diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index b3178cb67a04..7d03971a2281 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -4325,7 +4325,7 @@ void nsPluginInstanceOwner::Paint(const nsRect& aDirtyRect)
   ConvertRelativeToWindowAbsolute(mOwner, rel, abs, *getter_AddRefs(containerWidget));
 
   // Convert to absolute pixel values for the dirty rect
-  nsIntRect absDirtyRect = nsRect::ToOutsidePixels(nsRect(abs, aDirtyRect.Size()), *mOwner->GetPresContext()->AppUnitsPerDevPixel());
+  nsIntRect absDirtyRect = nsRect(abs, aDirtyRect.Size()).ToOutsidePixels(*mOwner->GetPresContext()->AppUnitsPerDevPixel());
 #endif
 
   nsCOMPtr<nsIPluginWidget> pluginWidget = do_QueryInterface(mWidget);
@@ -4369,7 +4369,7 @@ void nsPluginInstanceOwner::Paint(const nsRect& aDirtyRect, HPS aHPS)
 
   nsPluginWindow * window;
   GetWindow(window);
-  nsIntRect relDirtyRect = nsRect::ToOutsidePixels(aDirtyRect, mOwner->PresContext()->AppUnitsPerDevPixel());
+  nsIntRect relDirtyRect = aDirtyRect.ToOutsidePixels(mOwner->PresContext()->AppUnitsPerDevPixel());
 
   // we got dirty rectangle in relative window coordinates, but we
   // need it in absolute units and in the (left, top, right, bottom) form
diff --git a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
index 34c86d11f474..c171e8d6e628 100644
--- a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
+++ b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
@@ -680,7 +680,7 @@ nsSVGForeignObjectFrame::InvalidateDirtyRect(nsSVGOuterSVGFrame* aOuter,
   nsCOMPtr<nsIDOMSVGMatrix> localTM;
   ctm->Translate(x, y, getter_AddRefs(localTM));
 
-  nsIntRect r = nsRect::ToOutsidePixels(aRect, presContext->AppUnitsPerDevPixel());
+  nsIntRect r = aRect.ToOutsidePixels(presContext->AppUnitsPerDevPixel());
   nsRect rect = GetTransformedRegion(r.x, r.y, r.width, r.height,
                                      localTM, presContext);
 
diff --git a/layout/svg/base/src/nsSVGIntegrationUtils.cpp b/layout/svg/base/src/nsSVGIntegrationUtils.cpp
index 1bf565e19c82..1167441f19b7 100644
--- a/layout/svg/base/src/nsSVGIntegrationUtils.cpp
+++ b/layout/svg/base/src/nsSVGIntegrationUtils.cpp
@@ -126,9 +126,9 @@ nsSVGIntegrationUtils::ComputeFrameEffectsRect(nsIFrame* aFrame,
   nsRect r = GetSVGBBox(firstFrame, aFrame, aOverflowRect, userSpaceRect);
   // r is relative to user space
   PRUint32 appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
-  nsIntRect p = nsRect::ToOutsidePixels(r, appUnitsPerDevPixel);
+  nsIntRect p = r.ToOutsidePixels(appUnitsPerDevPixel);
   p = filterFrame->GetFilterBBox(firstFrame, &p);
-  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
+  r = p.ToAppUnits(appUnitsPerDevPixel);
   // Make it relative to aFrame again
   return r + userSpaceRect.TopLeft() - aFrame->GetOffsetTo(firstFrame);
 }
@@ -157,9 +157,9 @@ nsSVGIntegrationUtils::GetInvalidAreaForChangedSource(nsIFrame* aFrame,
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame);
   nsPoint offset = aFrame->GetOffsetTo(firstFrame) - userSpaceRect.TopLeft();
   nsRect r = aInvalidRect + offset;
-  nsIntRect p = nsRect::ToOutsidePixels(r, appUnitsPerDevPixel);
+  nsIntRect p = r.ToOutsidePixels(appUnitsPerDevPixel);
   p = filterFrame->GetInvalidationBBox(firstFrame, p);
-  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
+  r = p.ToAppUnits(appUnitsPerDevPixel);
   return r - offset;
 }
 
@@ -180,9 +180,9 @@ nsSVGIntegrationUtils::GetRequiredSourceForInvalidArea(nsIFrame* aFrame,
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame);
   nsPoint offset = aFrame->GetOffsetTo(firstFrame) - userSpaceRect.TopLeft();
   nsRect r = aDamageRect + offset;
-  nsIntRect p = nsRect::ToOutsidePixels(r, appUnitsPerDevPixel);
+  nsIntRect p = r.ToOutsidePixels(appUnitsPerDevPixel);
   p = filterFrame->GetSourceForInvalidArea(firstFrame, p);
-  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
+  r = p.ToAppUnits(appUnitsPerDevPixel);
   return r - offset;
 }
 
@@ -212,7 +212,7 @@ public:
     nsIRenderingContext::AutoPushTranslation push(ctx, -mOffset.x, -mOffset.y);
     nsRect dirty;
     if (aDirtyRect) {
-      dirty = nsIntRect::ToAppUnits(*aDirtyRect, nsIDeviceContext::AppUnitsPerCSSPixel());
+      dirty = aDirtyRect->ToAppUnits(nsIDeviceContext::AppUnitsPerCSSPixel());
       dirty += mOffset;
     } else {
       dirty = mInnerList->GetBounds(mBuilder);
@@ -281,7 +281,7 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(nsIRenderingContext* aCtx,
 
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame) + aBuilder->ToReferenceFrame(firstFrame);
   PRInt32 appUnitsPerDevPixel = aEffectsFrame->PresContext()->AppUnitsPerDevPixel();
-  userSpaceRect = nsIntRect::ToAppUnits(nsRect::ToNearestPixels(userSpaceRect, appUnitsPerDevPixel), appUnitsPerDevPixel);
+  userSpaceRect = userSpaceRect.ToNearestPixels(appUnitsPerDevPixel).ToAppUnits(appUnitsPerDevPixel);
   aCtx->Translate(userSpaceRect.x, userSpaceRect.y);
 
   nsCOMPtr<nsIDOMSVGMatrix> matrix = GetInitialMatrix(aEffectsFrame);
@@ -306,7 +306,7 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(nsIRenderingContext* aCtx,
   /* Paint the child */
   if (filterFrame) {
     RegularFramePaintCallback paint(aBuilder, aInnerList, userSpaceRect.TopLeft());
-    nsIntRect r = nsRect::ToOutsidePixels(aDirtyRect - userSpaceRect.TopLeft(), appUnitsPerDevPixel);
+    nsIntRect r = (aDirtyRect - userSpaceRect.TopLeft()).ToOutsidePixels(appUnitsPerDevPixel);
     filterFrame->FilterPaint(&svgContext, aEffectsFrame, &paint, &r);
   } else {
     gfx->SetMatrix(savedCTM);
diff --git a/layout/svg/base/src/nsSVGOuterSVGFrame.cpp b/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
index 137179ab1d46..084ee83e0298 100644
--- a/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
+++ b/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
@@ -553,7 +553,7 @@ nsSVGOuterSVGFrame::Paint(nsIRenderingContext& aRenderingContext,
   PRTime start = PR_Now();
 #endif
 
-  nsIntRect dirtyPxRect = nsRect::ToOutsidePixels(dirtyRect, PresContext()->AppUnitsPerDevPixel());
+  nsIntRect dirtyPxRect = dirtyRect.ToOutsidePixels(PresContext()->AppUnitsPerDevPixel());
 
   nsSVGRenderState ctx(&aRenderingContext);
 
diff --git a/layout/svg/base/src/nsSVGUtils.cpp b/layout/svg/base/src/nsSVGUtils.cpp
index 1547cbf3cc42..2750b5569933 100644
--- a/layout/svg/base/src/nsSVGUtils.cpp
+++ b/layout/svg/base/src/nsSVGUtils.cpp
@@ -512,7 +512,7 @@ nsRect
 nsSVGUtils::FindFilterInvalidation(nsIFrame *aFrame, const nsRect& aRect)
 {
   PRInt32 appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
-  nsIntRect rect = nsRect::ToOutsidePixels(aRect, appUnitsPerDevPixel);
+  nsIntRect rect = aRect.ToOutsidePixels(appUnitsPerDevPixel);
 
   while (aFrame) {
     if (aFrame->GetStateBits() & NS_STATE_IS_OUTER_SVG)
@@ -565,7 +565,7 @@ nsSVGUtils::FindFilterInvalidation(nsIFrame *aFrame, const nsRect& aRect)
     aFrame = aFrame->GetParent();
   }
 
-  return nsIntRect::ToAppUnits(rect, appUnitsPerDevPixel);
+  return rect.ToAppUnits(appUnitsPerDevPixel);
 }
 
 void
@@ -932,7 +932,7 @@ nsSVGUtils::PaintFrameWithEffects(nsSVGRenderState *aContext,
       if (!aDirtyRect->Intersects(filterFrame->GetFilterBBox(aFrame, nsnull)))
         return;
     } else {
-      nsRect rect = nsIntRect::ToAppUnits(*aDirtyRect, aFrame->PresContext()->AppUnitsPerDevPixel());
+      nsRect rect = aDirtyRect->ToAppUnits(aFrame->PresContext()->AppUnitsPerDevPixel());
       if (!rect.Intersects(aFrame->GetRect()))
         return;
     }
diff --git a/layout/xul/base/src/nsMenuPopupFrame.cpp b/layout/xul/base/src/nsMenuPopupFrame.cpp
index 0caa5fd6759f..270bc6a09fae 100644
--- a/layout/xul/base/src/nsMenuPopupFrame.cpp
+++ b/layout/xul/base/src/nsMenuPopupFrame.cpp
@@ -1052,7 +1052,7 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, PRBool aIsMove)
                              &screenRectPixels.width, &screenRectPixels.height);
     }
   }
-  nsRect screenRect = nsIntRect::ToAppUnits(screenRectPixels, presContext->AppUnitsPerDevPixel());
+  nsRect screenRect = screenRectPixels.ToAppUnits(presContext->AppUnitsPerDevPixel());
 
   // keep a 3 pixel margin to the right and bottom of the screen for the WinXP dropshadow
   screenRect.SizeBy(-nsPresContext::CSSPixelsToAppUnits(3),
diff --git a/layout/xul/base/src/nsScrollBoxObject.cpp b/layout/xul/base/src/nsScrollBoxObject.cpp
index f3fd087dd237..5520e55069ea 100644
--- a/layout/xul/base/src/nsScrollBoxObject.cpp
+++ b/layout/xul/base/src/nsScrollBoxObject.cpp
@@ -290,7 +290,7 @@ NS_IMETHODIMP nsScrollBoxObject::ScrollToElement(nsIDOMElement *child)
 
     nsIntRect prect;
     GetOffsetRect(prect);
-    crect = nsIntRect::ToAppUnits(prect, nsPresContext::AppUnitsPerCSSPixel());
+    crect = prect.ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
     nscoord newx=cp.x, newy=cp.y;
 
     // we only scroll in the direction of the scrollbox orientation
@@ -390,7 +390,7 @@ NS_IMETHODIMP nsScrollBoxObject::EnsureElementIsVisible(nsIDOMElement *child)
     scrollableView->GetScrollPosition(cp.x,cp.y);
     nsIntRect prect;
     GetOffsetRect(prect);
-    crect = nsIntRect::ToAppUnits(prect, nsPresContext::AppUnitsPerCSSPixel());
+    crect = prect.ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
 
     nscoord newx=cp.x, newy=cp.y;
 
diff --git a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
index f06ac8ba4fe8..b31b13b6b905 100644
--- a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
@@ -648,7 +648,7 @@ nsTreeBodyFrame::GetSelectionRegion(nsIScriptableRegion **aRegion)
   region->Init();
 
   nsRefPtr<nsPresContext> presContext = PresContext();
-  nsIntRect rect = nsRect::ToOutsidePixels(mRect, presContext->AppUnitsPerCSSPixel());
+  nsIntRect rect = mRect.ToOutsidePixels(presContext->AppUnitsPerCSSPixel());
 
   nsIFrame* rootFrame = presContext->PresShell()->GetRootFrame();
   nsPoint origin = GetOffsetTo(rootFrame);
diff --git a/view/src/nsScrollPortView.cpp b/view/src/nsScrollPortView.cpp
index 4faa8970d3ce..9875a757270c 100644
--- a/view/src/nsScrollPortView.cpp
+++ b/view/src/nsScrollPortView.cpp
@@ -578,8 +578,8 @@ void nsScrollPortView::Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsIntP
           }
         }
         toScrollPtr = &toScroll;
-        toScroll = nsRect::ToInsidePixels(biggestRect, aP2A);
-        biggestRect = nsIntRect::ToAppUnits(toScroll, aP2A);
+        toScroll = biggestRect.ToInsidePixels(aP2A);
+        biggestRect = toScroll.ToAppUnits(aP2A);
         regionToScroll.Sub(regionToScroll, biggestRect);
         updateRegion.Or(updateRegion, regionToScroll);
       }
diff --git a/view/src/nsView.cpp b/view/src/nsView.cpp
index 2bc45cfcf9c5..9142b151993c 100644
--- a/view/src/nsView.cpp
+++ b/view/src/nsView.cpp
@@ -379,7 +379,7 @@ nsIntRect nsView::CalcWidgetBounds(nsWindowType aType)
     }
   }
 
-  nsIntRect newBounds = nsRect::ToNearestPixels(viewBounds, p2a);
+  nsIntRect newBounds = viewBounds.ToNearestPixels(p2a);
 
   nsPoint roundedOffset(NSIntPixelsToAppUnits(newBounds.x, p2a),
                         NSIntPixelsToAppUnits(newBounds.y, p2a));
@@ -759,9 +759,9 @@ void nsIView::List(FILE* out, PRInt32 aIndent) const
     NS_RELEASE(dx);
     nsIntRect rect;
     mWindow->GetClientBounds(rect);
-    nsRect windowBounds = nsIntRect::ToAppUnits(rect, p2a);
+    nsRect windowBounds = rect.ToAppUnits(p2a);
     mWindow->GetBounds(rect);
-    nsRect nonclientBounds = nsIntRect::ToAppUnits(rect, p2a);
+    nsRect nonclientBounds = rect.ToAppUnits(p2a);
     nsrefcnt widgetRefCnt = mWindow->AddRef() - 1;
     mWindow->Release();
     PRInt32 Z;
diff --git a/view/src/nsViewManager.cpp b/view/src/nsViewManager.cpp
index 61bf2e3181ff..5252dd3508ef 100644
--- a/view/src/nsViewManager.cpp
+++ b/view/src/nsViewManager.cpp
@@ -1113,7 +1113,7 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
           region->GetBoundingBox(&damIntRect.x, &damIntRect.y,
                                  &damIntRect.width, &damIntRect.height);
           nsRect damRect =
-            nsIntRect::ToAppUnits(damIntRect, mContext->AppUnitsPerDevPixel());
+            damIntRect.ToAppUnits(mContext->AppUnitsPerDevPixel());
 
           nsIWidget* widget = view->GetNearestWidget(nsnull);
           if (widget && widget->GetTransparencyMode() == eTransparencyOpaque) {
@@ -2015,7 +2015,7 @@ nsIntRect nsViewManager::ViewToWidget(nsView *aView, nsView* aWidgetView, const
   rect += aView->ViewToWidgetOffset();
 
   // finally, convert to device coordinates.
-  return nsRect::ToOutsidePixels(rect, mContext->AppUnitsPerDevPixel());
+  return rect.ToOutsidePixels(mContext->AppUnitsPerDevPixel());
 }
 
 nsresult nsViewManager::GetVisibleRect(nsRect& aVisibleRect)
diff --git a/widget/src/xpwidgets/nsBaseDragService.cpp b/widget/src/xpwidgets/nsBaseDragService.cpp
index c7c0dc77a0e3..7884510e97a1 100644
--- a/widget/src/xpwidgets/nsBaseDragService.cpp
+++ b/widget/src/xpwidgets/nsBaseDragService.cpp
@@ -450,9 +450,8 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
       if (rootFrame && *aPresContext) {
         nsIntRect dragRect;
         aRegion->GetBoundingBox(&dragRect.x, &dragRect.y, &dragRect.width, &dragRect.height);
-        dragRect = nsRect::ToOutsidePixels(nsIntRect::ToAppUnits(dragRect,
-                                                                 nsPresContext::AppUnitsPerCSSPixel()),
-                                           (*aPresContext)->AppUnitsPerDevPixel());
+        dragRect = dragRect.ToAppUnits(nsPresContext::AppUnitsPerCSSPixel()).
+                            ToOutsidePixels((*aPresContext)->AppUnitsPerDevPixel());
 
         nsIntRect screenRect = rootFrame->GetScreenRectExternal();
         aScreenDragRect->SetRect(screenRect.x + dragRect.x, screenRect.y + dragRect.y,