What are the "must know" concepts in Qt framework?

[TheIndependentAquarius]

3) Understanding of Qt fundamentals:
-- The basic features of QObject.
-- Signals, slots, and connect.
-- Event-driven programming as used by Qt (and many other UI-oriented languages/dialects). Ie, a knowledge of what the "event loop" is and why it needs to be calling the shots.
-- Qt's parent/child mechanism.
-- The basic features and functions of QWidget.
-- How to find information for a Qt class or function in the online documentation.

Helpful post, thank you too

[aamer4yu]

I would say go through topics in Qt Assistant home page, and have a look at all Qt Demos...
thats a must know in my opinion, since it will give u an idea of all the features of Qt, and with demo u can find where to start for a program in most of cases if you are a newbie.