note: forward declaration of 'class QLineEdit'

QT 4 support forward declaration

orward declaration is not supported as:

//#include 
//class QCheckBox;
//class QLabel;
//class QLineEdit;
//class QPushButton;

must be replaced by:

#include 
#include 
#include 
#include 
#include 
#include 

QT4.82 support forward declaration, QT5.3 doesn't.