diff -r 000000000000 -r 6474c204b198 layout/xul/nsGroupBoxFrame.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/nsGroupBoxFrame.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,244 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// YY need to pass isMultiple before create called
+
+#include "nsBoxFrame.h"
+#include "nsCSSRendering.h"
+#include "nsRenderingContext.h"
+#include "nsStyleContext.h"
+#include "nsDisplayList.h"
+
+class nsGroupBoxFrame : public nsBoxFrame {
+public:
+  NS_DECL_FRAMEARENA_HELPERS
+
+  nsGroupBoxFrame(nsIPresShell* aShell, nsStyleContext* aContext):
+    nsBoxFrame(aShell, aContext) {}
+
+  virtual nsresult GetBorderAndPadding(nsMargin& aBorderAndPadding);
+
+  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                const nsRect&           aDirtyRect,
+                                const nsDisplayListSet& aLists) MOZ_OVERRIDE;
+
+#ifdef DEBUG_FRAME_DUMP
+  virtual nsresult GetFrameName(nsAString& aResult) const {
+    return MakeFrameName(NS_LITERAL_STRING("GroupBoxFrame"), aResult);
+  }
+#endif
+
+  virtual bool HonorPrintBackgroundSettings() { return false; }
+
+  void PaintBorderBackground(nsRenderingContext& aRenderingContext,
+      nsPoint aPt, const nsRect& aDirtyRect);
+
+  // make sure we our kids get our orient and align instead of us.
+  // our child box has no content node so it will search for a parent with one.
+  // that will be us.
+  virtual void GetInitialOrientation(bool& aHorizontal) { aHorizontal = false; }
+  virtual bool GetInitialHAlignment(Halignment& aHalign)  { aHalign = hAlign_Left; return true; } 
+  virtual bool GetInitialVAlignment(Valignment& aValign)  { aValign = vAlign_Top; return true; } 
+  virtual bool GetInitialAutoStretch(bool& aStretch)    { aStretch = true; return true; } 
+
+  nsIFrame* GetCaptionBox(nsPresContext* aPresContext, nsRect& aCaptionRect);
+};
+
+/*
+class nsGroupBoxInnerFrame : public nsBoxFrame {
+public:
+
+    nsGroupBoxInnerFrame(nsIPresShell* aShell, nsStyleContext* aContext):
+      nsBoxFrame(aShell, aContext) {}
+
+
+#ifdef DEBUG_FRAME_DUMP
+  NS_IMETHOD GetFrameName(nsString& aResult) const {
+    return MakeFrameName("GroupBoxFrameInner", aResult);
+  }
+#endif
+  
+  // we are always flexible
+  virtual bool GetDefaultFlex(int32_t& aFlex) { aFlex = 1; return true; }
+
+};
+*/
+
+nsIFrame*
+NS_NewGroupBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
+{
+  return new (aPresShell) nsGroupBoxFrame(aPresShell, aContext);
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsGroupBoxFrame)
+
+class nsDisplayXULGroupBackground : public nsDisplayItem {
+public:
+  nsDisplayXULGroupBackground(nsDisplayListBuilder* aBuilder,
+                              nsGroupBoxFrame* aFrame) :
+    nsDisplayItem(aBuilder, aFrame) {
+    MOZ_COUNT_CTOR(nsDisplayXULGroupBackground);
+  }
+#ifdef NS_BUILD_REFCNT_LOGGING
+  virtual ~nsDisplayXULGroupBackground() {
+    MOZ_COUNT_DTOR(nsDisplayXULGroupBackground);
+  }
+#endif
+
+  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                       HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames) {
+    aOutFrames->AppendElement(mFrame);
+  }
+  virtual void Paint(nsDisplayListBuilder* aBuilder,
+                     nsRenderingContext* aCtx);
+  NS_DISPLAY_DECL_NAME("XULGroupBackground", TYPE_XUL_GROUP_BACKGROUND)
+};
+
+void
+nsDisplayXULGroupBackground::Paint(nsDisplayListBuilder* aBuilder,
+                                   nsRenderingContext* aCtx)
+{
+  static_cast<nsGroupBoxFrame*>(mFrame)->
+    PaintBorderBackground(*aCtx, ToReferenceFrame(), mVisibleRect);
+}
+
+void
+nsGroupBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                  const nsRect&           aDirtyRect,
+                                  const nsDisplayListSet& aLists)
+{
+  // Paint our background and border
+  if (IsVisibleForPainting(aBuilder)) {
+    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+      nsDisplayXULGroupBackground(aBuilder, this));
+    
+    DisplayOutline(aBuilder, aLists);
+  }
+
+  BuildDisplayListForChildren(aBuilder, aDirtyRect, aLists);
+}
+
+void
+nsGroupBoxFrame::PaintBorderBackground(nsRenderingContext& aRenderingContext,
+    nsPoint aPt, const nsRect& aDirtyRect) {
+  int skipSides = 0;
+  const nsStyleBorder* borderStyleData = StyleBorder();
+  const nsMargin& border = borderStyleData->GetComputedBorder();
+  nscoord yoff = 0;
+  nsPresContext* presContext = PresContext();
+
+  nsRect groupRect;
+  nsIFrame* groupBox = GetCaptionBox(presContext, groupRect);
+
+  if (groupBox) {        
+    // if the border is smaller than the legend. Move the border down
+    // to be centered on the legend. 
+    nsMargin groupMargin;
+    groupBox->StyleMargin()->GetMargin(groupMargin);
+    groupRect.Inflate(groupMargin);
+ 
+    if (border.top < groupRect.height)
+        yoff = (groupRect.height - border.top)/2 + groupRect.y;
+  }
+
+  nsRect rect(aPt.x, aPt.y + yoff, mRect.width, mRect.height - yoff);
+
+  groupRect += aPt;
+
+  nsCSSRendering::PaintBackground(presContext, aRenderingContext, this,
+                                  aDirtyRect, rect,
+                                  nsCSSRendering::PAINTBG_SYNC_DECODE_IMAGES);
+
+  if (groupBox) {
+
+    // we should probably use PaintBorderEdges to do this but for now just use clipping
+    // to achieve the same effect.
+
+    // draw left side
+    nsRect clipRect(rect);
+    clipRect.width = groupRect.x - rect.x;
+    clipRect.height = border.top;
+
+    aRenderingContext.PushState();
+    aRenderingContext.IntersectClip(clipRect);
+    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                aDirtyRect, rect, mStyleContext, skipSides);
+
+    aRenderingContext.PopState();
+
+
+    // draw right side
+    clipRect = rect;
+    clipRect.x = groupRect.XMost();
+    clipRect.width = rect.XMost() - groupRect.XMost();
+    clipRect.height = border.top;
+
+    aRenderingContext.PushState();
+    aRenderingContext.IntersectClip(clipRect);
+    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                aDirtyRect, rect, mStyleContext, skipSides);
+
+    aRenderingContext.PopState();
+
+    
+  
+    // draw bottom
+
+    clipRect = rect;
+    clipRect.y += border.top;
+    clipRect.height = mRect.height - (yoff + border.top);
+  
+    aRenderingContext.PushState();
+    aRenderingContext.IntersectClip(clipRect);
+    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                aDirtyRect, rect, mStyleContext, skipSides);
+
+    aRenderingContext.PopState();
+    
+  } else {
+    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
+                                aDirtyRect, nsRect(aPt, GetSize()),
+                                mStyleContext, skipSides);
+  }
+}
+
+nsIFrame*
+nsGroupBoxFrame::GetCaptionBox(nsPresContext* aPresContext, nsRect& aCaptionRect)
+{
+    // first child is our grouped area
+    nsIFrame* box = GetChildBox();
+
+    // no area fail.
+    if (!box)
+      return nullptr;
+
+    // get the first child in the grouped area, that is the caption
+    box = box->GetChildBox();
+
+    // nothing in the area? fail
+    if (!box)
+      return nullptr;
+
+    // now get the caption itself. It is in the caption frame.
+    nsIFrame* child = box->GetChildBox();
+
+    if (child) {
+       // convert to our coordinates.
+       nsRect parentRect(box->GetRect());
+       aCaptionRect = child->GetRect();
+       aCaptionRect.x += parentRect.x;
+       aCaptionRect.y += parentRect.y;
+    }
+
+    return child;
+}
+
+nsresult
+nsGroupBoxFrame::GetBorderAndPadding(nsMargin& aBorderAndPadding)
+{
+  aBorderAndPadding.SizeTo(0,0,0,0);
+  return NS_OK;
+}
+