From f5d85dbba6307ac3cc252d39ae1dcc33423b11c9 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Thu, 28 Jun 2018 23:12:08 +0200
Subject: [PATCH] Convert the button rect to device coordinates correctly
 instead of casting CSS coordinates.

This should the correct fix for #559
---
 dom/base/nsGlobalWindow.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 4e384c4d21..884ad69ca5 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -14633,7 +14633,9 @@ nsGlobalWindow::NotifyDefaultButtonLoaded(Element& aDefaultButton,
     return;
   }
   LayoutDeviceIntRect buttonRect =
-    LayoutDeviceIntRect::FromUnknownRect(frame->GetScreenRect());
+    LayoutDeviceIntRect::FromAppUnitsToNearest(
+      frame->GetScreenRectInAppUnits(),
+      frame->PresContext()->AppUnitsPerDevPixel());
 
   // Get the widget rect in screen coordinates.
   nsIWidget *widget = GetNearestWidget();