title: When offsetdescendantrecttomycoords is used?
body: <p>I was following an online tutorial, and he used off offsetdescendantrecttomycoords. I researched a lot, but was unable to find any satisfactory  explanation. I referred to the docs and it says 
   "Offset a rectangle that is in a descendant's coordinate space into our coordinate space"
   I dont get it.. what is our coordinate space ??</p>
  
  <p>Any help is appreciated.</p>