It is implemented using the mentioned widgets. For methods, you can write wrapper which decide to which subwidget this method should be delegated, or just to handle the method itself. But it's easier to use the standard mechanisms of Tk. It removes the burden of option and method handling. Composite widgets are container widgets like Toplevel s or Frame s and contain other widgets in it, for example to form a dialog.
Derived widgets are already existing widgets with additional or changed functionality.
You should be familiar with the object oriented concepts of Perl. There is the perltoot manpage included in the Perl distribution, which contains an object-oriented tutorial by Tom Christiansen. This widget is rather small in code size, but already contains a lot of magic behind the scenes. The LabEntry widget The LabEntry widget is a frame widget embedded with a label widget and an entry widget. In short, it's just an entry with a description label attached to a side.