diff --git a/src/calibre/ebooks/oeb/polish/preview.coffee b/src/calibre/ebooks/oeb/polish/preview.coffee
index f218cc26bd..e596e1c6bd 100644
--- a/src/calibre/ebooks/oeb/polish/preview.coffee
+++ b/src/calibre/ebooks/oeb/polish/preview.coffee
@@ -17,6 +17,21 @@ is_hidden = (elem) ->
         elem = elem.parentNode
     return false
 
+previous_sibling = (node) ->
+    node = node.previousSibling
+    while node and node.nodeType != Node.ELEMENT_NODE
+        node = node.previousSibling
+    return node
+
+is_block = (elem) ->
+    style = window.getComputedStyle(elem)
+    return style.display in ['block', 'flex-box', 'box']
+
+find_containing_block = (elem) ->
+    while elem and elem.getAttribute('data-is-block') != '1'
+        elem = elem.parentNode
+    return elem
+
 class PreviewIntegration
 
     ###
@@ -27,18 +42,20 @@ class PreviewIntegration
     constructor: () ->
         if not this instanceof arguments.callee
             throw new Error('PreviewIntegration constructor called as function')
+        this.blocks_found = false
+        this.in_split_mode = false
 
-    go_to_line: (lnum) ->
+    go_to_line: (lnum) =>
         for node in document.querySelectorAll('[data-lnum="' + lnum + '"]')
             if is_hidden(node)
                 continue
             top = window.calibre_utils.abstop(node) - (window.innerHeight / 2)
-            if (top < 0)
+            if top < 0
                 top = 0
             window.scrollTo(0, top)
             return
 
-    line_numbers: () ->
+    line_numbers: () =>
         found_body = false
         ans = []
         for node in document.getElementsByTagName('*')
@@ -49,18 +66,43 @@ class PreviewIntegration
         return ans
 
     find_blocks: () =>
+        if this.blocks_found
+            return
         for elem in document.body.getElementsByTagName('*')
-            style = window.getComputedStyle(elem)
-            if style.display in ['block', 'flex-box', 'box']
+            if is_block(elem)
                 elem.setAttribute('data-is-block', '1')
-                elem.onclick = this.onclick
+        this.blocks_found = true
 
-    onload: () ->
-        window.document.body.addEventListener('click', window.calibre_preview_integration.onclick, true)
+    split_mode: (enabled) =>
+        this.in_split_mode = enabled
+        document.body.setAttribute('data-in-split-mode', if enabled then '1' else '0')
+        if enabled
+            this.find_blocks()
 
-    onclick: (event) ->
+    report_split: (node) =>
+        loc = []
+        parent = find_containing_block(node)
+        while parent and parent.tagName.toLowerCase() != 'body'
+            num = 0
+            sibling = previous_sibling(parent)
+            while sibling
+                num += 1
+                sibling = previous_sibling(sibling)
+            loc.push(num)
+            parent = parent.parentNode
+        loc.reverse()
+        window.py_bridge.request_split(loc)
+
+    onload: () =>
+        window.document.body.addEventListener('click', this.onclick, true)
+
+    onclick: (event) =>
         event.preventDefault()
-        window.py_bridge.request_sync(event.target.getAttribute("data-lnum"))
+        if this.in_split_mode
+            this.report_split(event.target)
+        else
+            window.py_bridge.request_sync(event.target.getAttribute("data-lnum"))
+        return false
 
 window.calibre_preview_integration = new PreviewIntegration()
 window.onload = window.calibre_preview_integration.onload
diff --git a/src/calibre/gui2/tweak_book/boss.py b/src/calibre/gui2/tweak_book/boss.py
index 12660743c8..68078066e6 100644
--- a/src/calibre/gui2/tweak_book/boss.py
+++ b/src/calibre/gui2/tweak_book/boss.py
@@ -57,6 +57,7 @@ class Boss(QObject):
         self.gui.central.close_requested.connect(self.editor_close_requested)
         self.gui.central.search_panel.search_triggered.connect(self.search)
         self.gui.preview.sync_requested.connect(self.sync_editor_to_preview)
+        self.gui.preview.split_start_requested.connect(self.split_start_requested)
 
     def mkdtemp(self, prefix=''):
         self.container_count += 1
@@ -502,6 +503,11 @@ class Boss(QObject):
         if ok:
             ed.current_line = num
 
+    def split_start_requested(self):
+        if not self.check_dirtied():
+            return self.gui.preview.stop_split()
+        self.gui.preview.do_start_split()
+
     def sync_editor_to_preview(self, name, lnum):
         editor = self.edit_file(name, 'html')
         self.ignore_preview_to_editor_sync = True
diff --git a/src/calibre/gui2/tweak_book/preview.py b/src/calibre/gui2/tweak_book/preview.py
index 4df502dd81..e28d92cae8 100644
--- a/src/calibre/gui2/tweak_book/preview.py
+++ b/src/calibre/gui2/tweak_book/preview.py
@@ -6,8 +6,9 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import time
+import time, textwrap
 from bisect import bisect_right
+from base64 import b64encode
 from future_builtins import map
 from threading import Thread
 from Queue import Queue, Empty
@@ -23,6 +24,7 @@ from calibre.constants import iswindows, DEBUG
 from calibre.ebooks.oeb.polish.parsing import parse
 from calibre.ebooks.oeb.base import serialize, OEB_DOCS
 from calibre.ptempfile import PersistentTemporaryDirectory
+from calibre.gui2 import error_dialog
 from calibre.gui2.tweak_book import current_container, editors, tprefs, actions
 from calibre.gui2.viewer.documentview import apply_settings
 from calibre.gui2.viewer.config import config
@@ -237,6 +239,7 @@ def find_le(a, x):
 class WebPage(QWebPage):
 
     sync_requested = pyqtSignal(object)
+    split_requested = pyqtSignal(object)
 
     def __init__(self, parent):
         QWebPage.__init__(self, parent)
@@ -251,6 +254,10 @@ class WebPage(QWebPage):
         settings.setAttribute(settings.LinksIncludedInFocusChain, False)
         settings.setAttribute(settings.DeveloperExtrasEnabled, True)
         settings.setDefaultTextEncoding('utf-8')
+        data = 'data:text/css;charset=utf-8;base64,'
+        css = '[data-in-split-mode="1"] [data-is-block="1"]:hover { cursor: pointer !important; border-top: solid 5px green !important }'
+        data += b64encode(css.encode('utf-8'))
+        settings.setUserStyleSheetUrl(QUrl(data))
 
         self.setNetworkAccessManager(NetworkAccessManager(self))
         self.setLinkDelegationPolicy(self.DelegateAllLinks)
@@ -277,6 +284,14 @@ class WebPage(QWebPage):
         except (TypeError, ValueError, OverflowError, AttributeError):
             pass
 
+    @pyqtSlot('QList<int>')
+    def request_split(self, loc):
+        actions['split-in-preview'].setChecked(False)
+        if not loc:
+            return error_dialog(self.view(), _('Invalid location'),
+                                _('Cannot split on the body tag'), show=True)
+        self.split_requested.emit(loc)
+
     @property
     def line_numbers(self):
         if self._line_numbers is None:
@@ -297,6 +312,12 @@ class WebPage(QWebPage):
         self.mainFrame().evaluateJavaScript(
             'window.calibre_preview_integration.go_to_line(%d)' % lnum)
 
+    def split_mode(self, enabled):
+        self.mainFrame().evaluateJavaScript(
+            'window.calibre_preview_integration.split_mode(%s)' % (
+                'true' if enabled else 'false'))
+
+
 class WebView(QWebView):
 
     def __init__(self, parent=None):
@@ -343,6 +364,8 @@ class WebView(QWebView):
 class Preview(QWidget):
 
     sync_requested = pyqtSignal(object, object)
+    split_requested = pyqtSignal(object, object)
+    split_start_requested = pyqtSignal()
 
     def __init__(self, parent=None):
         QWidget.__init__(self, parent)
@@ -351,6 +374,8 @@ class Preview(QWidget):
         l.setContentsMargins(0, 0, 0, 0)
         self.view = WebView(self)
         self.view.page().sync_requested.connect(self.request_sync)
+        self.view.page().split_requested.connect(self.request_split)
+        self.view.page().loadFinished.connect(self.load_finished)
         self.inspector = self.view.inspector
         self.inspector.setPage(self.view.page())
         l.addWidget(self.view)
@@ -373,6 +398,13 @@ class Preview(QWidget):
 
         self.bar.addSeparator()
 
+        ac = actions['split-in-preview']
+        ac.setCheckable(True)
+        ac.setChecked(False)
+        ac.toggled.connect(self.split_toggled)
+        self.split_toggled(ac.isChecked())
+        self.bar.addAction(ac)
+
         ac = actions['reload-preview']
         ac.triggered.connect(self.refresh)
         self.bar.addAction(ac)
@@ -390,6 +422,10 @@ class Preview(QWidget):
         if self.current_name:
             self.sync_requested.emit(self.current_name, lnum)
 
+    def request_split(self, loc):
+        if self.current_name:
+            self.split_requested.emit(self.current_name, loc)
+
     def sync_to_editor(self, name, lnum):
         self.current_sync_request = (name, lnum)
         QTimer.singleShot(100, self._sync_to_editor)
@@ -455,3 +491,26 @@ class Preview(QWidget):
         if is_visible:
             self.refresh()
 
+    def split_toggled(self, checked):
+        actions['split-in-preview'].setToolTip(textwrap.fill(_(
+            'Abort file split') if checked else _(
+                'Split this file at a specified location.\n\nAfter clicking this button, click'
+                ' inside the preview panel above at the location you want the file to be split.')))
+        if checked:
+            self.split_start_requested.emit()
+        else:
+            self.view.page().split_mode(False)
+
+    def do_start_split(self):
+        self.view.page().split_mode(True)
+
+    def stop_split(self):
+        actions['split-in-preview'].setChecked(False)
+
+    def load_finished(self, ok):
+        if actions['split-in-preview'].isChecked():
+            if ok:
+                self.do_start_split()
+            else:
+                self.stop_split()
+
diff --git a/src/calibre/gui2/tweak_book/ui.py b/src/calibre/gui2/tweak_book/ui.py
index d3882fba52..144a8d7593 100644
--- a/src/calibre/gui2/tweak_book/ui.py
+++ b/src/calibre/gui2/tweak_book/ui.py
@@ -223,6 +223,8 @@ class Main(MainWindow):
         self.action_auto_sync_preview = reg('sync-right.png', _('Sync preview position to editor position'), None, 'sync-preview-to-editor', (), _(
             'Sync preview position to editor position'))
         self.action_reload_preview = reg('view-refresh.png', _('Refresh preview'), None, 'reload-preview', ('F5',), _('Refresh preview'))
+        self.action_split_in_preview = reg('auto_author_sort.png', _('Split this file'), None, 'split-in-preview', (), _(
+            'Split file in the preview panel'))
 
         # Search actions
         group = _('Search')