Описание тега qevent
A QEvent is a class from the Qt toolkit which forms the base class of all other event classes.
QEvent objects act as containers for event parameters.
The Qt main event loop fetches native window system events from the event queue, translates them into QEvents, and sends the translated events to QObjects (which receive them via their event() function). It is also possible to manually create and send events.
Each subclass of QEvent contains additional parameters to describe that particular event type.
The official Qt documentation can be found here for Qt 4.8 and here for Qt 5.