From 86455fc5f34119f2b989470ee1fca1db51e53d4f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 20 Jun 2012 11:01:13 +0530
Subject: [PATCH 1/2] ...

---
 src/calibre/gui2/viewer/documentview.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/calibre/gui2/viewer/documentview.py b/src/calibre/gui2/viewer/documentview.py
index ad8bff76d4..8c6da27d71 100644
--- a/src/calibre/gui2/viewer/documentview.py
+++ b/src/calibre/gui2/viewer/documentview.py
@@ -928,6 +928,13 @@ class DocumentView(QWebView): # {{{
                 self.document.scroll_to(x=loc, y=0)
                 if self.manager is not None:
                     self.manager.scrolled(self.scroll_fraction)
+                event.accept()
+            elif self.manager is not None:
+                if direction == 'next':
+                    self.manager.next_document()
+                else:
+                    self.manager.previous_document()
+                event.accept()
             return
 
         if event.delta() < -14:

From fcdd96c2bb5b49959326ced7deeddff7131e3196 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 20 Jun 2012 12:20:32 +0530
Subject: [PATCH 2/2] Speed up rendering in paged mode by not causing an extra
 re-layout to adjust the top margin of body

---
 src/calibre/ebooks/oeb/display/paged.coffee | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/calibre/ebooks/oeb/display/paged.coffee b/src/calibre/ebooks/oeb/display/paged.coffee
index 6096326d7e..454c50bb87 100644
--- a/src/calibre/ebooks/oeb/display/paged.coffee
+++ b/src/calibre/ebooks/oeb/display/paged.coffee
@@ -82,6 +82,17 @@ class PagedDisplay
         this.cols_per_screen = cols_per_screen
 
     layout: () ->
+        # Remove the top margin from the first child of body as that gets added
+        # to the top margin of body. This is done here just in case
+        # getComputedStyle() causes a relayout. The re-layout will be much
+        # faster before we implement the multi-column layout.
+        for node in document.body.childNodes
+            if node.nodeType == 1 # Element node
+                style = window.getComputedStyle(node)
+                if style.display in ['block', 'table']
+                    node.style.setProperty('margin-top', '0px')
+                    break
+
         ww = window.innerWidth
         wh = window.innerHeight
         body_height = wh - this.margin_bottom = this.margin_top
@@ -135,11 +146,6 @@ class PagedDisplay
                             priority = rule.style.getPropertyPriority(prop)
                             rule.style.setProperty(cprop, val, priority)
 
-        # Ensure that the top margin is correct, otherwise for some documents,
-        # webkit lays out the body with a lot of space on top
-        brect = document.body.getBoundingClientRect()
-        if brect.top > this.margin_top
-            bs.setProperty('margin-top', (this.margin_top - brect.top)+'px')
         this.in_paged_mode = true
         this.current_margin_side = sm
         return sm