And of course, the download link is: http://www.squeaksource.com/WatchIt.html

2009/1/11 Hernán Morales Durand <hernan.morales@gmail.com>
Dear all,
  You can use again the "Watch It" debugging functionality written by Ned Konz back in 2002. This is the description:

"This adds a 'watch it' choice to the context menus in text editors. This will take the selection, make a BlockContext out of it, and give you a Morph that will display the value of that block every half second. It can be used, for instance, from the Debugger to display an instance variable as your program runs."

Test 1:
Paint and select "watch it" from the menu:

World currentHand cursorPoint

Test 2:
"debug it" the following lines, once inside the debugger, paint the "collection", select "watch it" and voilà!

| collection |
collection := #(1 2 3 4) asOrderedCollection.
collection add: 88.
collection add: 99.
collection

Tested under:
-Squeak3.9
-Squeak3.10.2
-Pharo0.1Core-10201

Cheers

Hernán