The QPaintEvent class contains event parameters for paint events. ... QPaintEvent  ( const QRect & paintRect )  . const QRect&  rect  () const . ... Paint events are sent to widgets that need to update themselves, for instance when a part of a widget is exposed because an overlying widget is moved away. The event handler QWidget::paintEvent () receives paint events. ... Constructs a paint event object with the rectangle that should be updated. ... qevent.h: 1998/07/03 . ...