Unsolved Is it possible to load Qt Designer custom widget plugin just like what does in Qt Designer?

[rickluo]

I'd like to load Qt Designer custom widget plugins (which implement QDesignerCustomWidgetInterface interface) and show a list of them in my app, just like what does in Qt Designer WidgetBox.

How to do that?

I tried to #include <QtUiPlugin/customwidget.h> in my application, but it don't compile. Error:
use undefined class QDesignerCustomWidgetInterface.
And my project profile is like this:
QT += core gui designer
TEMPLATE = app