The QWhatsThis class provides a simple description of any widget, i.e. answering the question "What's This?".| doc.qt.io
Function Documentation| doc.qt.io
The QWidget class is the base class of all user interface objects.| doc.qt.io
The QEvent class is the base class of all event classes. Event objects contain event parameters.| doc.qt.io
The QAction class provides an abstraction for user commands that can be added to different user interface components.| doc.qt.io
The Qt namespace contains miscellaneous identifiers used throughout the Qt library.| doc.qt.io