diff --git a/.gitignore b/.gitignore
index d7fe4be24..4c88e89c2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,4 +32,5 @@ koreader-arm-linux-gnueabi
 koreader-arm-linux-gnueabihf
 koreader-i686-w64-mingw32
 koreader-x86_64-linux-gnu
+koreader-x86_64-pc-linux-gnu
 
diff --git a/frontend/ui/message/streammessagequeue.lua b/frontend/ui/message/streammessagequeue.lua
index bf51a005b..58ed30931 100644
--- a/frontend/ui/message/streammessagequeue.lua
+++ b/frontend/ui/message/streammessagequeue.lua
@@ -57,7 +57,13 @@ end
 
 function StreamMessageQueue:waitEvent()
     local data = ""
-    while czmq.zpoller_wait(self.poller, 0) ~= nil do
+    -- Successive zframes may be tens or hundreds in some cases
+    -- if they are concatenated in a single loop it may run up memory of the
+    -- machine. And it did happened when receiving file data from Calibre server.
+    -- Here we receive only receive 10 packages at most in one waitEvent loop, and
+    -- call receiveCallback immediately.
+    local wait_packages = 10
+    while czmq.zpoller_wait(self.poller, 0) ~= nil and wait_packages > 0 do
         local id_frame = czmq.zframe_recv(self.socket)
         if id_frame ~= nil then
             local id = self:handleZframe(id_frame)
@@ -66,6 +72,7 @@ function StreamMessageQueue:waitEvent()
         if frame ~= nil then
             data = data .. (self:handleZframe(frame) or "")
         end
+        wait_packages = wait_packages - 1
     end
     if self.receiveCallback and data ~= "" then
         self.receiveCallback(data)
diff --git a/frontend/ui/uimanager.lua b/frontend/ui/uimanager.lua
index e9a1de150..de9beb7d8 100644
--- a/frontend/ui/uimanager.lua
+++ b/frontend/ui/uimanager.lua
@@ -322,7 +322,9 @@ function UIManager:run()
         local force_partial_refresh = false
         local force_fast_refresh = false
         for _, widget in ipairs(self._window_stack) do
-            if self.repaint_all or self._dirty[widget.widget] then
+            -- paint if repaint_all is request
+            -- paint also if current widget or any widget underneath is dirty
+            if self.repaint_all or dirty or self._dirty[widget.widget] then
                 widget.widget:paintTo(Screen.bb,
                                       widget.x + Screen:offsetX(),
                                       widget.y + Screen:offsetY())
diff --git a/plugins/calibrecompanion.koplugin/main.lua b/plugins/calibrecompanion.koplugin/main.lua
index 69afa6310..440c079e8 100644
--- a/plugins/calibrecompanion.koplugin/main.lua
+++ b/plugins/calibrecompanion.koplugin/main.lua
@@ -332,6 +332,7 @@ function CalibreCompanion:sendBook(arg)
     -- switching to raw data receiving mode
     self.calibre_socket.receiveCallback = function(data)
         --DEBUG("receive file data", #data)
+        --DEBUG("Memory usage KB:", collectgarbage("count"))
         local to_write_data = data:sub(1, to_write_bytes)
         outfile:write(to_write_data)
         to_write_bytes = to_write_bytes - #to_write_data