Why do almost all UI examples rely heavily on concrete inheritance?  As I looked for tutorials, examples, and references, I kept seeing concrete inheritance come up.  It is bad design and it muddles up the examples.  Are they creating a function in the class for their own use or are they overriding a method?  How critical is it they override it to be able to get functionality X?

PyGTK tutorial and reference were great.  Everything is easily found in the reference and almost everything I needed to know was in the tutorial.  Qt's reference is good, PyQt's is a bit more so-so.  As for tutorials I have not found one concrete tutorial that covers 90% of what I need but instead need to jump from tutorial to tutorial depending on the specific thing I am doing.  I've even done searches through source code to try and find how to use somethings but that didn't get me much.