In the designer when I right click a widget, and I click promote to I get this window. See the screenshot below.
I have never used this feature. Basically, the header file is confusing me. What is it for? Does that mean I can create a new class in this case, inheriting QLineEdit and add more methods to it? What is the promoted class name?
This allows you to use custom widgets defined elsewhere, which designer otherwise wouldn't know about.
For example, if you've defined a widget MyLabel derived from QLabel, then you can define it here and then just insert a QLabel as placeholder in your ui and promote it to MyLabel.
The uic compiler will then include the necessary imports/includes, for example if you specified mypackage/mycomponent.h as header file and MyLabel as class name, then pyuic will add
from mypackage.mycomponent import MyLabel
(note how the .h is ignored, and slashes are converted to . by pyuic to keep compatibility with python)
Global include is ignored by pyuic, it only affects uic (generate #include "mypackage/mycomponent.h" or #include <mypackage/mycomponent.h> for c++)
来源：https://stackoverflow.com/questions/19622014/how-do-i-use-promote-to-in-qt-designer-in-pyqt4