//VC程序
#include "../QTDLL/ExportDll.h"

int _tmain(int argc, _TCHAR* argv[])
{
  printf("%d",add(1));
  return 0;
}

DLL

#include "stdafx.h"
#include "ExportDll.h"
#include "ui_DLG.h"
int add(int a)
{
  QApplication ap(a,NULL);
  QWidget* w  = new QWidget();
  Ui_Form s;  
  s.setupUi(w);
  s.pushButton->winId()

  w->show();
  ap.exec();
  return a+1;

}