One of the things that I love about Squeak is its environment. Once you get past the beginner stage, it offers a wealth of exploration goodness. One of my favorite tricks is when I want to learn how something is done, I simply go through the menu options of a morph while it's on screen (you can get a menu on any morph via the halos). I find the option I want to know about and then alt-click twice. This brings up the halos for the menu item. I then simply debug it (since the menu item is a morph as well). The inspector shows you all the information for the menu item including what it calls when clicked. It's a great way to learn how morphs are put together.
It might not seem like much, but I love the fact that everything in morphic is inspectable and changeable. It makes playing a lot of fun. Morphic can be frustrating sometimes, but I love how easy it is to find out how things are put together with it.
I can't wait to start playing around with Tweak and see how it is.