There is a lack of clarity in where to use Blender menu, panel or the operator. I am familiar with inheritance in Qt where QDialog, QWidget, QMessageBox, QMainWindow are used as required. As a matter of fact ncurses library and wx also has similar inheritance pattern. I know there is no relation between Blender and Qt, or wx or ncurses but I was trying to learn from the Blender Python documents and information is very sparse. Is there any secret manual available somewhere? Also I'm not keeping any other library as a template to compare against Blender types, I'm just new to the whole of Blender.