These classes are abstract widgets; they are generally not usable in
themselves, but provide functionality that can be used by inheriting
these classes.
Classes:
QButton
(The abstract base class of button widgets, providing functionality common to buttons)
QFrame
(The base class of widgets that (can) have a frame)
QScrollView
(Scrolling area with on-demand scrollbars)
QTableView
(This is an abstract base class for implementing tables)
QWidget
(The base class of all user interface objects)
