[LXDE] Lock screen in LUbuntu via shortcut

LUbuntu users may encounter a bug that prevents them from locking the screen either from command line or keyboard shortcut.

In my case, solving it was quite easy:

First install lxlock and light-locker, you might already have them:

sudo apt-get install lxlock light-locker

Then edit ~//.config/openbox/lubuntu-rc.xml and modify or add the lockscreen section:

  <!-- Lock the screen on W + L-->  
  <keybind key="W-L">  
   <action name="Execute">  
    <command>lxlock</command>  
   </action>  
 </keybind>  

Finally restart openbox:

openbox --restart