Programming :: Popup A Dialog On Application Start?

Anyway, here is something that is puzzling me and cannot think up a good way around it: I call the constructor and show elements of LoginDialog in the constructor of my QMainWindow, like this:

PHP Code:

MainWindow::MainWindow(QWidget *parent) :    QMainWindow(parent),    ui(new Ui::MainWindow){    ui->setupUi(this);    LoginDialog *lid = new LoginDialog(this);    lid.show();} 

LoginDialog is a QDialog and it does show up on application start... but...
It is not active! The QMainWindow is the active window, even if I put lid->activateWindow();

So, the question is: how do I pop up this dialog on application start in such a way that it will show the LoginDialog on startup as active window?