title: How to find filepath relative from one absolute to another?
body: <p>e.g. myfunc(from:c:\my\dir,to:c:\my\other\file.ext) ==> ..\other\file.ext .</p>
  
  <p><strong>new Uri()</strong> need not apply, unless there's a remedy for it returning URI format not Windows filename format. .LocalPath fails.</p>