diff --git a/base b/base
index 959f8c216..3260f0494 160000
--- a/base
+++ b/base
@@ -1 +1 @@
-Subproject commit 959f8c2160abee41b846158b2b06820617427b38
+Subproject commit 3260f0494f7558f234806e68adb92606af391f8f
diff --git a/frontend/apps/reader/modules/readerdictionary.lua b/frontend/apps/reader/modules/readerdictionary.lua
index e1ee8d2f7..398df95e5 100644
--- a/frontend/apps/reader/modules/readerdictionary.lua
+++ b/frontend/apps/reader/modules/readerdictionary.lua
@@ -32,21 +32,24 @@ function ReaderDictionary:onLookupWord(word, box, highlight)
     return true
 end
 
-local function tidyCDATA(results)
+local function tidy_markup(results)
     local cdata_tag = "<!%[CDATA%[(.-)%]%]>"
     local format_escape = "&[29Ib%+]{(.-)}"
     for _, result in ipairs(results) do
+        local def = result.definition
+        -- preserve the <br> tag for line break
+        def = def:gsub("<[bB][rR] ?/?>", "\n")
         -- parse CDATA text in XML
-        if result.definition:find(cdata_tag) then
-            local def = result.definition:gsub(cdata_tag, "%1")
-            -- ignore all tags
-            def = def:gsub("%b<>", "")
+        if def:find(cdata_tag) then
+            def = def:gsub(cdata_tag, "%1")
             -- ignore format strings
             while def:find(format_escape) do
                 def = def:gsub(format_escape, "%1")
             end
-            result.definition = def
         end
+        -- ignore all markup tags
+        def = def:gsub("%b<>", "")
+        result.definition = def
     end
     return results
 end
@@ -66,7 +69,7 @@ function ReaderDictionary:stardictLookup(word, box)
         local ok, results = pcall(JSON.decode, JSON, results_str)
         if ok and results then
             DEBUG("lookup result table:", word, results)
-            self:showDict(word, tidyCDATA(results), box)
+            self:showDict(word, tidy_markup(results), box)
         else
             -- dummy results
             results = {
diff --git a/frontend/apps/reader/modules/readermenu.lua b/frontend/apps/reader/modules/readermenu.lua
index 8c79c3c90..da688f5bf 100644
--- a/frontend/apps/reader/modules/readermenu.lua
+++ b/frontend/apps/reader/modules/readermenu.lua
@@ -46,7 +46,6 @@ function ReaderMenu:init()
                 local FileManager = require("apps/filemanager/filemanager")
                 FileManager:restoreScreenMode()
                 if not FileManager.is_running then
-                    UIManager:quit()
                     FileManager:showFiles()
                 end
             end,
@@ -91,8 +90,6 @@ function ReaderMenu:setUpdateItemTable()
     end
 
     -- setting tab
-    -- FIXME: it's curious that if this 'Screen' menu is placed after the Language
-    -- menu submenu in 'Screen' won't be shown. Probably a bug in the touchmenu module.
     table.insert(self.tab_item_table.setting, {
         text = _("Screen settings"),
         sub_item_table = {
@@ -143,27 +140,33 @@ function ReaderMenu:setUpdateItemTable()
         end
     })
 
-    --typeset tab
     if KOBO_SCREEN_SAVER_LAST_BOOK then
-        local exclude = self.ui.doc_settings:readSetting("exclude_screensaver") or false
+        local excluded = function()
+            return self.ui.doc_settings:readSetting("exclude_screensaver") or false
+        end
+        local proportional = function()
+            return self.ui.doc_settings:readSetting("proportional_screensaver") or false
+        end
         table.insert(self.tab_item_table.typeset, {
-            text = _("Use this book's cover as screensaver"),
-            checked_func = function() return not (self.ui.doc_settings:readSetting("exclude_screensaver") or false) end,
-            callback = function()
-                local exclude = self.ui.doc_settings:readSetting("exclude_screensaver") or false
-                self.ui.doc_settings:saveSetting("exclude_screensaver", not exclude)
-                self.ui:saveSettings()
-            end
-        })
-        local proportional = self.ui.doc_settings:readSetting("proportional_screensaver") or false
-        table.insert(self.tab_item_table.typeset, {
-            text = _("Display proportional cover image in screensaver"),
-            checked_func = function() return (self.ui.doc_settings:readSetting("proportional_screensaver") or false) end,
-            callback = function()
-                local proportional = self.ui.doc_settings:readSetting("proportional_screensaver") or false
-                self.ui.doc_settings:saveSetting("proportional_screensaver", not proportional)
-                self.ui:saveSettings()
-            end
+            text = "Screensaver",
+            sub_item_table = {
+                {
+                    text = _("Use this book's cover as screensaver"),
+                    checked_func = function() return not excluded() end,
+                    callback = function()
+                        self.ui.doc_settings:saveSetting("exclude_screensaver", not excluded())
+                        self.ui:saveSettings()
+                    end
+                },
+                {
+                    text = _("Display proportional cover image in screensaver"),
+                    checked_func = function() return proportional() end,
+                    callback = function()
+                        self.ui.doc_settings:saveSetting("proportional_screensaver", not proportional())
+                        self.ui:saveSettings()
+                    end
+                }
+            }
         })
     end
 end
diff --git a/frontend/cache.lua b/frontend/cache.lua
index a7306a619..a2455148e 100644
--- a/frontend/cache.lua
+++ b/frontend/cache.lua
@@ -136,8 +136,11 @@ function Cache:serialize()
     -- serialize the most recently used cache
     local cache_size = 0
     for _, key in ipairs(self.cache_order) do
-        if self.cache[key].dump then
-            cache_size = self.cache[key]:dump(cache_path..md5(key)) or 0
+        local cache_item = self.cache[key]
+        -- only dump cache item that requests serialization explicitly
+        if cache_item.persistent and cache_item.dump then
+            DEBUG("dump cache item", key)
+            cache_size = cache_item:dump(cache_path..md5(key)) or 0
             if cache_size > 0 then break end
         end
     end
diff --git a/frontend/document/document.lua b/frontend/document/document.lua
index 535e09893..f274b6dda 100644
--- a/frontend/document/document.lua
+++ b/frontend/document/document.lua
@@ -1,11 +1,12 @@
-local DrawContext = require("ffi/drawcontext")
-local Blitbuffer = require("ffi/blitbuffer")
-local Cache = require("cache")
-local CacheItem = require("cacheitem")
 local TileCacheItem = require("document/tilecacheitem")
-local Geom = require("ui/geometry")
+local DrawContext = require("ffi/drawcontext")
 local Configurable = require("configurable")
+local Blitbuffer = require("ffi/blitbuffer")
+local lfs = require("libs/libkoreader-lfs")
+local CacheItem = require("cacheitem")
+local Geom = require("ui/geometry")
 local Math = require("optmath")
+local Cache = require("cache")
 local DEBUG = require("dbg")
 
 --[[
@@ -114,6 +115,7 @@ function Document:getNativePageDimensions(pageno)
 end
 
 function Document:_readMetadata()
+    self.mod_time = lfs.attributes(self.file, "modification")
     self.info.number_of_pages = self._document:getPages()
     return true
 end
@@ -215,8 +217,13 @@ function Document:getCoverPageImage()
     return nil
 end
 
+function Document:getFullPageHash(pageno, zoom, rotation, gamma, render_mode)
+    return "renderpg|"..self.file.."|"..self.mod_time.."|"..pageno.."|"
+                    ..zoom.."|"..rotation.."|"..gamma.."|"..render_mode
+end
+
 function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode)
-    local hash = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..gamma.."|"..render_mode
+    local hash = self:getFullPageHash(pageno, zoom, rotation, gamma, render_mode)
     local page_size = self:getPageDimensions(pageno, zoom, rotation)
     -- this will be the size we actually render
     local size = page_size
@@ -231,12 +238,13 @@ function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode)
             return
         end
         -- only render required part
-        hash = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..gamma.."|"..render_mode.."|"..tostring(rect)
+        hash = self:getFullPageHash(pageno, zoom, rotation, gamma, render_mode).."|"..tostring(rect)
         size = rect
     end
 
     -- prepare cache item with contained blitbuffer
     local tile = TileCacheItem:new{
+        persistent = true,
         size = size.w * size.h + 64, -- estimation
         excerpt = size,
         pageno = pageno,
@@ -274,7 +282,7 @@ end
 -- a hint for the cache engine to paint a full page to the cache
 -- TODO: this should trigger a background operation
 function Document:hintPage(pageno, zoom, rotation, gamma, render_mode)
-    local hash_full_page = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..gamma.."|"..render_mode
+    local hash_full_page = self:getFullPageHash(pageno, zoom, rotation, gamma, render_mode)
     if not Cache:check(hash_full_page, TileCacheItem) then
         DEBUG("hinting page", pageno)
         self:renderPage(pageno, nil, zoom, rotation, gamma, render_mode)
@@ -290,7 +298,7 @@ Draw page content to blitbuffer.
 @rect: visible_area inside document page
 --]]
 function Document:drawPage(target, x, y, rect, pageno, zoom, rotation, gamma, render_mode)
-    local hash_full_page = "renderpg|"..self.file.."|"..pageno.."|"..zoom.."|"..rotation.."|"..gamma.."|"..render_mode
+    local hash_full_page = self:getFullPageHash(pageno, zoom, rotation, gamma, render_mode)
     local hash_excerpt = hash_full_page.."|"..tostring(rect)
     local tile = Cache:check(hash_full_page, TileCacheItem)
     if not tile then
diff --git a/frontend/document/koptinterface.lua b/frontend/document/koptinterface.lua
index 2193f5e29..368a78e37 100644
--- a/frontend/document/koptinterface.lua
+++ b/frontend/document/koptinterface.lua
@@ -107,7 +107,8 @@ function KoptInterface:getContextHash(doc, pageno, bbox)
     local screen_size = Screen:getSize()
     local screen_size_hash = screen_size.w.."|"..screen_size.h
     local bbox_hash = bbox.x0.."|"..bbox.y0.."|"..bbox.x1.."|"..bbox.y1
-    return doc.file.."|"..pageno.."|"..doc.configurable:hash("|").."|"..bbox_hash.."|"..screen_size_hash
+    return doc.file.."|"..doc.mod_time.."|"..pageno.."|"
+            ..doc.configurable:hash("|").."|"..bbox_hash.."|"..screen_size_hash
 end
 
 function KoptInterface:getPageBBox(doc, pageno)
@@ -215,6 +216,7 @@ function KoptInterface:getCachedContext(doc, pageno)
         DEBUG("reflowed page", pageno, "fullwidth:", fullwidth, "fullheight:", fullheight)
         self.last_context_size = fullwidth * fullheight + 128 -- estimation
         Cache:insert(kctx_hash, ContextCacheItem:new{
+            persistent = true,
             size = self.last_context_size,
             kctx = kc
         })
@@ -289,7 +291,7 @@ function KoptInterface:renderReflowedPage(doc, pageno, rect, zoom, rotation, ren
         end
         -- prepare cache item with contained blitbuffer
         local tile = TileCacheItem:new{
-            size = fullwidth * fullheight / 2 + 64, -- estimation
+            size = fullwidth * fullheight + 64, -- estimation
             excerpt = Geom:new{ w = fullwidth, h = fullheight },
             pageno = pageno,
         }
@@ -311,7 +313,7 @@ function KoptInterface:renderOptimizedPage(doc, pageno, rect, zoom, rotation, re
     local context_hash = self:getContextHash(doc, pageno, bbox)
     local renderpg_hash = "renderoptpg|"..context_hash..zoom
 
-    local cached = Cache:check(renderpg_hash)
+    local cached = Cache:check(renderpg_hash, TileCacheItem)
     if not cached then
         local page_size = Document.getNativePageDimensions(doc, pageno)
         local bbox = {
@@ -329,7 +331,8 @@ function KoptInterface:renderOptimizedPage(doc, pageno, rect, zoom, rotation, re
         local fullwidth, fullheight = kc:getPageDim()
         -- prepare cache item with contained blitbuffer
         local tile = TileCacheItem:new{
-            size = fullwidth * fullheight / 2 + 64, -- estimation
+            persistent = true,
+            size = fullwidth * fullheight + 64, -- estimation
             excerpt = Geom:new{
                 x = 0, y = 0,
                 w = fullwidth,
diff --git a/frontend/ui/uimanager.lua b/frontend/ui/uimanager.lua
index de9beb7d8..72a5d234a 100644
--- a/frontend/ui/uimanager.lua
+++ b/frontend/ui/uimanager.lua
@@ -132,10 +132,20 @@ function UIManager:init()
 end
 
 -- register & show a widget
+-- modal widget should be always on the top
 function UIManager:show(widget, x, y)
+    DEBUG("show widget", widget.id)
     self._running = true
-    -- put widget on top of stack
-    table.insert(self._window_stack, {x = x or 0, y = y or 0, widget = widget})
+    local window = {x = x or 0, y = y or 0, widget = widget}
+    -- put this window on top of the toppest non-modal window
+    for i = #self._window_stack, 0, -1 do
+        local top_window = self._window_stack[i]
+        -- skip modal window
+        if not top_window or not top_window.widget.modal then
+            table.insert(self._window_stack, i + 1, window)
+            break
+        end
+    end
     -- and schedule it to be painted
     self:setDirty(widget)
     -- tell the widget that it is shown now
@@ -148,6 +158,7 @@ end
 
 -- unregister a widget
 function UIManager:close(widget)
+    DEBUG("close widget", widget.id)
     Input.disable_double_tap = DGESDETECT_DISABLE_DOUBLE_TAP
     local dirty = false
     for i = #self._window_stack, 1, -1 do
@@ -226,6 +237,7 @@ end
 
 -- signal to quit
 function UIManager:quit()
+    DEBUG("quit uimanager")
     self._running = false
     for i = #self._window_stack, 1, -1 do
         table.remove(self._window_stack, i)
diff --git a/frontend/ui/widget/confirmbox.lua b/frontend/ui/widget/confirmbox.lua
index f21240d9b..fd7a02427 100644
--- a/frontend/ui/widget/confirmbox.lua
+++ b/frontend/ui/widget/confirmbox.lua
@@ -24,6 +24,7 @@ local Blitbuffer = require("ffi/blitbuffer")
 Widget that shows a message and OK/Cancel buttons
 ]]
 local ConfirmBox = InputContainer:new{
+    modal = true,
     text = _("no text"),
     face = Font:getFace("infofont", 25),
     ok_text = _("OK"),
diff --git a/frontend/ui/widget/infomessage.lua b/frontend/ui/widget/infomessage.lua
index cc006c586..adb8f4731 100644
--- a/frontend/ui/widget/infomessage.lua
+++ b/frontend/ui/widget/infomessage.lua
@@ -21,6 +21,7 @@ Widget that displays an informational message
 it vanishes on key press or after a given timeout
 ]]
 local InfoMessage = InputContainer:new{
+    modal = true,
     face = Font:getFace("infofont", 25),
     text = "",
     timeout = nil, -- in seconds
diff --git a/frontend/ui/widget/touchmenu.lua b/frontend/ui/widget/touchmenu.lua
index b0ea0883b..080dcec8b 100644
--- a/frontend/ui/widget/touchmenu.lua
+++ b/frontend/ui/widget/touchmenu.lua
@@ -103,6 +103,7 @@ function TouchMenuItem:onTapSelect(arg, ges)
         UIManager:setDirty(self.show_parent, "partial")
     end)
     self.menu:onMenuSelect(self.item)
+    return true
 end
 
 function TouchMenuItem:onHoldSelect(arg, ges)
@@ -119,6 +120,7 @@ function TouchMenuItem:onHoldSelect(arg, ges)
         UIManager:setDirty(self.show_parent, "partial")
     end)
     self.menu:onMenuHold(self.item)
+    return true
 end
 
 --[[
@@ -331,11 +333,11 @@ function TouchMenu:init()
         self.device_info = HorizontalGroup:new{
             self.time_info,
             self.net_info,
-        } 
-    else 
+        }
+    else
         self.device_info = HorizontalGroup:new{
             self.time_info,
-        } 
+        }
     end
     local footer_width = self.width - self.padding*2 - self.bordersize*2
     self.footer = HorizontalGroup:new{