How to detect if a window has been activated?

Question

Focus events don't work because they're not sent if you activate your window by clicking on its non-client frame. Also, if you click the internal components of the window THEY will get the focus event, not your window, but the window will still be activated, even if it wasn't active or focused before.

Answer 1

Qt provides several virtual event handling functions you can use. Since the activation of a window changes its state, you want to handle some change events:

void MyWidget::changeEvent(QEvent * e) {
    if(e->type() == QEvent::ActivationChange && this->isActiveWindow()) {
       // .. this is now the active window      
    }
}

References

• changeEvent
• isActiveWindow