Constructs a mouse event object.
The type parameter must be one of QEvent::MouseButtonPress, QEvent::MouseButtonRelease, QEvent::MouseButtonDblClick, or QEvent::MouseMove.
The position is the mouse cursor's position relative to the receiving widget. The button that caused the event is given as a value from the Qt::MouseButton enum. If the event type is MouseMove, the appropriate button for this event is Qt::NoButton. The mouse and keyboard states at the time of the event are specified by buttons and modifiers.