QWidget setFocus does nothing

Question

I am implementing a custom context menu that is basically a widget called gripmenu containing several other widgets. If the user left clicks, this menu should appear. To hide or delete it if the user clicks outside of it, I need to somehow check if the user click somewhere else. My plan is to ask all its child widgets for ->hasFocus() and if none hasFocus, I will close the menu. But unfortunately I can't set the focus. Why? My code is:

gripmenu = new GripMenu(this);
gripmenu->setFocus();

And in the gripmenu's constructor:

GripMenu::GripMenu(){
  [... set things up]
  ui->lineEdit->setFocus(); // or any other widget to focus, 
                            // even this->setFocus() does not work: see below:
  qDebug() << ui->lineEdit->hasFocus(); // returns false!
}

How is it possible that there is no focus immediately after I just set it?

At the end my goal is to mimic a typical context-menu behaviour (meaning that the menu is closed when clicked somewhere else). So if you have better suggestions on how to tackle it, please hint me that way!

EDIT:

I got it working. The hint of Frank Osterfeld was really useful. Still I had to add a "gripmenu->activate()" in the widget "A" that created(needed) the gripmenu, because without it, the active widget would still be "A" after the mouse got released.

Answer 1

Try the code below, it should work:

QTimer::singleShot(0, lineEdit, SLOT(setFocus()));