screen orientation won't change when going into filemanager

and filemanager remembers screen orientation at exit
This should fix #1338.

frontend/apps/filemanager/filemanager.lua

@@ -155,6 +155,20 @@ function FileManager:init()
     self:handleEvent(Event:new("SetDimensions", self.dimen))
 end
 
+function FileManager:resetDimen(dimen)
+    self.dimen = dimen
+    -- backup the root path and path items
+    self.root_path = self.file_chooser.path
+    local path_items_backup = {}
+    for k, v in pairs(self.file_chooser.path_items) do
+        path_items_backup[k] = v
+    end
+    -- reinit filemanager
+    self:init()
+    self.file_chooser.path_items = path_items_backup
+    self:onRefresh()
+end
+
 function FileManager:toggleHiddenFiles()
     self.file_chooser:toggleHiddenFiles()
     G_reader_settings:saveSetting("show_hidden", self.file_chooser.show_hidden)
@@ -172,6 +186,7 @@ end
 
 function FileManager:onClose()
     DEBUG("close filemanager")
+    G_reader_settings:saveSetting("fm_screen_mode", Screen:getScreenMode())
     UIManager:close(self)
     if self.onExit then
         self:onExit()
@@ -206,15 +221,17 @@ function FileManager:showFiles(path)
     DEBUG("show home page")
     path = path or G_reader_settings:readSetting("lastdir") or self:getDefaultDir()
     G_reader_settings:saveSetting("lastdir", path)
-    UIManager:show(FileManager:new{
+    self:restoreScreenMode()
+    local file_manager = FileManager:new{
         dimen = Screen:getSize(),
         root_path = path,
         onExit = function()
-            self.is_running = false
+            self.instance = nil
             UIManager:quit()
         end
-    })
-    self.is_running = true
+    }
+    UIManager:show(file_manager)
+    self.instance = file_manager
 end
 
 function FileManager:copyFile(file)

frontend/apps/reader/modules/readermenu.lua

@@ -40,11 +40,10 @@ function ReaderMenu:init()
             callback = function()
                 self:onTapCloseMenu()
                 self.ui:onClose()
-                -- screen orientation is independent for docview and filemanager
-                -- so we need to restore the screen mode for the filemanager
                 local FileManager = require("apps/filemanager/filemanager")
-                FileManager:restoreScreenMode()
-                if not FileManager.is_running then
+                if FileManager.instance then
+                    FileManager.instance:resetDimen(Screen:getSize())
+                else
                     local lastdir = nil
                     local last_file = G_reader_settings:readSetting("lastfile")
                     if last_file then

frontend/ui/widget/filechooser.lua

@@ -26,7 +26,7 @@ local FileChooser = Menu:extend{
     strcoll = strcoll,
     collate = "strcoll", -- or collate = "access",
     reverse_collate = false,
-    path_pages = {}, -- store last browsed location(page) for each path
+    path_items = {}, -- store last browsed location(item index) for each path
 }
 
 function FileChooser:init()
@@ -150,12 +150,11 @@ end
 
 function FileChooser:updateItems(select_number)
     Menu.updateItems(self, select_number) -- call parent's updateItems()
-    self.path_pages[self.path] = self.page
+    self.path_items[self.path] = (self.page - 1) * self.perpage + (select_number or 1)
 end
 
 function FileChooser:refreshPath()
-    self.page = self.path_pages[self.path] or 1
-    self:swithItemTable(nil, self:genItemTableFromPath(self.path), -1)
+    self:swithItemTable(nil, self:genItemTableFromPath(self.path), self.path_items[self.path])
 end
 
 function FileChooser:changeToPath(path)