Question

These classes are useful classes not fitting into any other category.

QAccel	Handles keyboard accelerator and shortcut keys
QAccessible	Enums and static functions relating to accessibility
QAccessibleInterface	Defines an interface that exposes information about accessible objects
QAccessibleObject	Implements parts of the QAccessibleInterface for QObjects
QCustomMenuItem	Abstract base class for custom menu items in popup menus
QDoubleValidator	Range checking of floating-point numbers
QErrorMessage	Error message display dialog
QFileIconProvider	Icons for QFileDialog to use
QFilePreview	File previewing in QFileDialog
QFocusData	Maintains the list of widgets in the focus chain
QIntValidator	Validator which ensures that a string contains a valid integer within a specified range
QKeySequence	Encapsulates a key sequence as used by accelerators
QMenuData	Base class for QMenuBar and QPopupMenu
QMimeSource	Abstraction of objects which provide formatted data of a certain MIME type
QProcess	Used to start external programs and to communicate with them
QRangeControl	Integer value within a range
QRegExp	Pattern matching using regular expressions
QRegExpValidator	Used to check a string against a regular expression
QSettings	Persistent platform-independent application settings
QSignal	Can be used to send signals for classes that don't inherit QObject
Qt	Namespace for miscellaneous identifiers that need to be global-like
QUrl	URL parser and simplifies working with URLs
QUrlInfo	Stores information about URLs
QUrlOperator	Common operations on URLs
QValidator	Validation of input text
QVariant	Acts like a union for the most common Qt data types
QWindowsMime	Maps open-standard MIME to Window Clipboard formats