Thank you for the feedback. I have changed the title a bit, so it is not so misleading, and I have added more comments about this snippet to include an example using Hook::LexWrap.

An example problem that this is a solution for, is that a user wants to plug in their USB drive and they want to copy their files to their PC. So, to be user friendly, you could use this snippet as a basis for showing progress while files are getting copied. You could insert Tk progressbars, show remaining bytes, etc.