title: How to check if file locked/used by other process NSIS
body: <p>Hi I am writing nsis script for a patch installer. Before installer copies new files I need to check if any process is using the files I want to replace and I want rename those files to tmp and delete them on reboot. 
  Is there any way installer can detect that if any process is using those files (in my case the files I am going to install are dlls).</p>