diff --git a/src/calibre/gui2/tweak_book/file_list.py b/src/calibre/gui2/tweak_book/file_list.py
index 838dd75d94..cb7a1d3880 100644
--- a/src/calibre/gui2/tweak_book/file_list.py
+++ b/src/calibre/gui2/tweak_book/file_list.py
@@ -25,7 +25,7 @@ from calibre.ebooks.oeb.polish.replace import get_recommended_folders
 from calibre.ebooks.oeb.polish.cover import (
     get_cover_page_name, get_raster_cover_name, is_raster_image)
 from calibre.gui2 import error_dialog, choose_files, question_dialog, elided_text, choose_save_file
-from calibre.gui2.tweak_book import current_container, tprefs
+from calibre.gui2.tweak_book import current_container, tprefs, editors
 from calibre.gui2.tweak_book.editor import syntax_from_mime
 from calibre.gui2.tweak_book.templates import template_for
 from calibre.utils.icu import sort_key
@@ -647,7 +647,7 @@ class FileList(QTreeWidget):
 
     @property
     def searchable_names(self):
-        ans = {'text':OrderedDict(), 'styles':OrderedDict(), 'selected':OrderedDict()}
+        ans = {'text':OrderedDict(), 'styles':OrderedDict(), 'selected':OrderedDict(), 'open':OrderedDict()}
         for item in self.all_files:
             category = unicode(item.data(0, CATEGORY_ROLE) or '')
             mime = unicode(item.data(0, MIME_ROLE) or '')
@@ -657,8 +657,14 @@ class FileList(QTreeWidget):
                 ans[category][name] = syntax_from_mime(name, mime)
             if not ok and category == 'misc':
                 ok = mime in {guess_type('a.'+x) for x in ('opf', 'ncx', 'txt', 'xml')}
-            if ok and item.isSelected():
-                ans['selected'][name] = syntax_from_mime(name, mime)
+            if ok:
+                cats = []
+                if item.isSelected():
+                    cats.append('selected')
+                if name in editors:
+                    cats.append('open')
+                for cat in cats:
+                    ans[cat][name] = syntax_from_mime(name, mime)
         return ans
 
     def export(self, name):
diff --git a/src/calibre/gui2/tweak_book/search.py b/src/calibre/gui2/tweak_book/search.py
index 619c9bce79..df8c841467 100644
--- a/src/calibre/gui2/tweak_book/search.py
+++ b/src/calibre/gui2/tweak_book/search.py
@@ -117,7 +117,7 @@ class WhereBox(QComboBox):
 
     def __init__(self, parent, emphasize=False):
         QComboBox.__init__(self)
-        self.addItems([_('Current file'), _('All text files'), _('All style files'), _('Selected files'), _('Marked text')])
+        self.addItems([_('Current file'), _('All text files'), _('All style files'), _('Selected files'), _('Open files'), _('Marked text')])
         self.setToolTip('<style>dd {margin-bottom: 1.5ex}</style>' + _(
             '''
             Where to search/replace:
@@ -130,6 +130,8 @@ class WhereBox(QComboBox):
             <dd>Search in all style (CSS) files</dd>
             <dt><b>Selected files</b></dt>
             <dd>Search in the files currently selected in the Files Browser</dd>
+            <dt><b>Open files</b></dt>
+            <dd>Search in the files currently open in the editor</dd>
             <dt><b>Marked text</b></dt>
             <dd>Search only within the marked text in the currently opened file. You can mark text using the Search menu.</dd>
             </dl>'''))
@@ -142,7 +144,7 @@ class WhereBox(QComboBox):
 
     @dynamic_property
     def where(self):
-        wm = {0:'current', 1:'text', 2:'styles', 3:'selected', 4:'selected-text'}
+        wm = {0:'current', 1:'text', 2:'styles', 3:'selected', 4:'open', 5:'selected-text'}
         def fget(self):
             return wm[self.currentIndex()]
         def fset(self, val):
@@ -1185,7 +1187,7 @@ def initialize_search_request(state, action, current_editor, current_editor_name
     marked = False
     if where == 'current':
         editor = current_editor
-    elif where in {'styles', 'text', 'selected'}:
+    elif where in {'styles', 'text', 'selected', 'open'}:
         files = searchable_names[where]
         if current_editor_name in files:
             # Start searching in the current editor
diff --git a/src/calibre/gui2/tweak_book/text_search.py b/src/calibre/gui2/tweak_book/text_search.py
index a754567b95..4af6c11dfc 100644
--- a/src/calibre/gui2/tweak_book/text_search.py
+++ b/src/calibre/gui2/tweak_book/text_search.py
@@ -47,7 +47,7 @@ class WhereBox(QComboBox):
 
     def __init__(self, parent, emphasize=False):
         QComboBox.__init__(self)
-        self.addItems([_('Current file'), _('All text files'), _('Selected files')])
+        self.addItems([_('Current file'), _('All text files'), _('Selected files'), _('Open files')])
         self.setToolTip('<style>dd {margin-bottom: 1.5ex}</style>' + _(
             '''
             Where to search/replace:
@@ -58,6 +58,8 @@ class WhereBox(QComboBox):
             <dd>Search in all text (HTML) files</dd>
             <dt><b>Selected files</b></dt>
             <dd>Search in the files currently selected in the Files Browser</dd>
+            <dt><b>Open files</b></dt>
+            <dd>Search in the files currently open in the editor</dd>
             </dl>'''))
         self.emphasize = emphasize
         self.ofont = QFont(self.font())
@@ -68,7 +70,7 @@ class WhereBox(QComboBox):
 
     @dynamic_property
     def where(self):
-        wm = {0:'current', 1:'text', 2:'selected'}
+        wm = {0:'current', 1:'text', 2:'selected', 3:'open'}
         def fget(self):
             return wm[self.currentIndex()]
         def fset(self, val):