Question

Here are the classes in Qt, with brief descriptions:

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
QAction	Abstract user interface action that can appear both in menus and tool bars
QActionGroup	Groups actions together
QApplication	Manages the GUI application's control flow and main settings
QAsciiCache	Template class that provides a cache based on char* keys
QAsciiCacheIterator	Iterator for QAsciiCache collections
QAsciiDict	Template class that provides a dictionary based on char* keys
QAsciiDictIterator	Iterator for QAsciiDict collections
QBitArray	Array of bits
QBitVal	Internal class, used with QBitArray
QBitmap	Monochrome (1-bit depth) pixmaps
QBoxLayout	Lines up child widgets horizontally or vertically
QBrush	Defines the fill pattern of shapes drawn by a QPainter
QBuffer	I/O device that operates on a QByteArray
QButton	The abstract base class of button widgets, providing functionality common to buttons
QButtonGroup	Organizes QButton widgets in a group
QByteArray	Array of bytes
QCDEStyle	CDE look and feel
QCString	Abstraction of the classic C zero-terminated char array (char *)
QCache	Template class that provides a cache based on QString keys
QCacheIterator	Iterator for QCache collections
QCanvas	2D area that can contain QCanvasItem objects
QCanvasEllipse	Ellipse or ellipse segment on a QCanvas
QCanvasItem	Abstract graphic object on a QCanvas
QCanvasItemList	List of QCanvasItems
QCanvasLine	Line on a QCanvas
QCanvasPixmap	Pixmaps for QCanvasSprites
QCanvasPixmapArray	Array of QCanvasPixmaps
QCanvasPolygon	Polygon on a QCanvas
QCanvasPolygonalItem	Polygonal canvas item on a QCanvas
QCanvasRectangle	Rectangle on a QCanvas
QCanvasSpline	Multi-bezier splines on a QCanvas
QCanvasSprite	Animated canvas item on a QCanvas
QCanvasText	Text object on a QCanvas
QCanvasView	On-screen view of a QCanvas
QChar	Lightweight Unicode character
QCharRef	Helper class for QString
QCheckBox	Checkbox with a text label
QCheckListItem	Checkable list view items
QCheckTableItem	Checkboxes in QTables
QChildEvent	Event parameters for child object events
QClipboard	Access to the window system clipboard
QCloseEvent	Parameters that describe a close event
QColor	Colors based on RGB or HSV values
QColorDialog	Dialog widget for specifying colors
QColorDrag	Drag and drop object for transferring colors
QColorGroup	Group of widget colors
QComboBox	Combined button and popup list
QComboTableItem	Means of using comboboxes in QTables
QCommonStyle	Encapsulates the common Look and Feel of a GUI
QConstString	String objects using constant Unicode data
QContextMenuEvent	Parameters that describe a context menu event
QCopChannel	Communication capabilities between several clients
QCursor	Mouse cursor with an arbitrary shape
QCustomEvent	Support for custom events
QCustomMenuItem	Abstract base class for custom menu items in popup menus
QDataBrowser	Data manipulation and navigation for data entry forms
QDataStream	Serialization of binary data to a QIODevice
QDataTable	Flexible SQL table widget that supports browsing and editing
QDataView	Read-only SQL forms
QDate	Date functions
QDateEdit	Date editor
QDateTime	Date and time functions
QDateTimeEdit	Combines a QDateEdit and QTimeEdit widget into a single widget for editing datetimes
QDesktopWidget	Access to screen information on multi-head systems
QDial	Rounded range control (like a speedometer or potentiometer)
QDialog	The base class of dialog windows
QDict	Template class that provides a dictionary based on QString keys
QDictIterator	Iterator for QDict collections
QDir	Access to directory structures and their contents in a platform-independent way
QDirectPainter	Direct access to the video hardware
QDns	Asynchronous DNS lookups
QDockArea	Manages and lays out QDockWindows
QDockWindow	Widget which can be docked inside a QDockArea or floated as a top level window on the desktop
QDomAttr	Represents one attribute of a QDomElement
QDomCDATASection	Represents an XML CDATA section
QDomCharacterData	Represents a generic string in the DOM
QDomComment	Represents an XML comment
QDomDocument	Represents an XML document
QDomDocumentFragment	Tree of QDomNodes which is not usually a complete QDomDocument
QDomDocumentType	The representation of the DTD in the document tree
QDomElement	Represents one element in the DOM tree
QDomEntity	Represents an XML entity
QDomEntityReference	Represents an XML entity reference
QDomImplementation	Information about the features of the DOM implementation
QDomNamedNodeMap	Collection of nodes that can be accessed by name
QDomNode	The base class for all the nodes in a DOM tree
QDomNodeList	List of QDomNode objects
QDomNotation	Represents an XML notation
QDomProcessingInstruction	Represents an XML processing instruction
QDomText	Represents text data in the parsed XML document
QDoubleValidator	Range checking of floating-point numbers
QDragEnterEvent	Event which is sent to the widget when a drag and drop first drags onto the widget
QDragLeaveEvent	Event which is sent to the widget when a drag and drop leaves the widget
QDragMoveEvent	Event which is sent while a drag and drop is in progress
QDragObject	Encapsulates MIME-based data transfer
QDropEvent	Event which is sent when a drag and drop is completed
QEditorFactory	Used to create editor widgets for QVariant data types
QErrorMessage	Error message display dialog
QEucJpCodec	Conversion to and from EUC-JP character sets
QEucKrCodec	Conversion to and from EUC-KR character sets
QEvent	The base class of all event classes. Event objects contain event parameters
QFile	I/O device that operates on files
QFileDialog	Dialogs that allow users to select files or directories
QFileIconProvider	Icons for QFileDialog to use
QFileInfo	System-independent file information
QFilePreview	File previewing in QFileDialog
QFocusData	Maintains the list of widgets in the focus chain
QFocusEvent	Event parameters for widget focus events
QFont	Font used for drawing text
QFontDatabase	Information about the fonts available in the underlying window system
QFontDialog	Dialog widget for selecting a font
QFontInfo	General information about fonts
QFontManager	Implements font management in Qt/Embedded
QFontMetrics	Font metrics information
QFrame	The base class of widgets that can have a frame
QFtp	Implementation of the FTP protocol
QGL	Namespace for miscellaneous identifiers in the Qt OpenGL module
QGLColormap	Used for installing custom colormaps into QGLWidgets
QGLContext	Encapsulates an OpenGL rendering context
QGLFormat	The display format of an OpenGL rendering context
QGLWidget	Widget for rendering OpenGL graphics
QGLayoutIterator	Abstract base class of internal layout iterators
QGb18030Codec	Conversion to and from the Chinese GB18030/GBK/GB2312 encoding
QGbkCodec	Conversion to and from the Chinese GBK encoding
QGrid	Simple geometry management of its children
QGridLayout	Lays out widgets in a grid
QGridView	Abstract base for fixed-size grids
QGroupBox	Group box frame with a title
QGuardedPtr	Template class that provides guarded pointers to QObjects
QHBox	Horizontal geometry management for its child widgets
QHBoxLayout	Lines up widgets horizontally
QHButtonGroup	Organizes QButton widgets in a group with one horizontal row
QHGroupBox	Organizes widgets in a group with one horizontal row
QHeader	Header row or column, e.g. for tables and listviews
QHebrewCodec	Conversion to and from visually ordered Hebrew
QHideEvent	Event which is sent after a widget is hidden
QHostAddress	IP address
QHttp	Implementation of the HTTP protocol
QIMEvent	Parameters for input method events
QIODevice	The base class of I/O devices
QIconDrag	Supports drag and drop operations within a QIconView
QIconDragItem	Encapsulates a drag item
QIconSet	Set of icons with different styles and sizes
QIconView	Area with movable labelled icons
QIconViewItem	Single item in a QIconView
QImage	Hardware-independent pixmap representation with direct access to the pixel data
QImageConsumer	Abstraction used by QImageDecoder
QImageDecoder	Incremental image decoder for all supported image formats
QImageDrag	Drag and drop object for transferring images
QImageFormat	Incremental image decoder for a specific image format
QImageFormatPlugin	Abstract base for custom image format plugins
QImageFormatType	Factory that makes QImageFormat objects
QImageIO	Parameters for loading and saving images
QInputDialog	Simple convenience dialog to get a single value from the user
QIntCache	Template class that provides a cache based on long keys
QIntCacheIterator	Iterator for QIntCache collections
QIntDict	Template class that provides a dictionary based on long keys
QIntDictIterator	Iterator for QIntDict collections
QIntValidator	Validator which ensures that a string contains a valid integer within a specified range
QJisCodec	Conversion to and from JIS character sets
QKeyEvent	Describes a key event
QKeySequence	Encapsulates a key sequence as used by accelerators
QLCDNumber	Displays a number with LCD-like digits
QLabel	Text or image display
QLayout	The base class of geometry managers
QLayoutItem	Abstract item that a QLayout manipulates
QLayoutIterator	Iterators over QLayoutItem
QLibrary	Wrapper for handling shared libraries
QLineEdit	One-line text editor
QListBox	List of selectable, read-only items
QListBoxItem	The base class of all list box items
QListBoxPixmap	List box items with a pixmap and optional text
QListBoxText	List box items that display text
QListView	Implements a list/tree view
QListViewItem	Implements a list view item
QListViewItemIterator	Iterator for collections of QListViewItems
QLocalFs	Implementation of a QNetworkProtocol that works on the local file system
QLock	Wrapper for a System V shared semaphore
QMainWindow	Main application window, with a menu bar, dock windows (e.g. for toolbars), and a status bar
QMap	Value-based template class that provides a dictionary
QMapConstIterator	Iterator for QMap
QMapIterator	Iterator for QMap
QMemArray	Template class that provides arrays of simple types
QMenuBar	Horizontal menu bar
QMenuData	Base class for QMenuBar and QPopupMenu
QMessageBox	Modal dialog with a short message, an icon, and some buttons
QMetaObject	Meta information about Qt objects
QMetaProperty	Stores meta data about a property
QMimeSource	Abstraction of objects which provide formatted data of a certain MIME type
QMimeSourceFactory	Extensible provider of mime-typed data
QMotifPlusStyle	More sophisticated Motif-ish look and feel
QMotifStyle	Motif look and feel
QMouseEvent	Parameters that describe a mouse event
QMoveEvent	Event parameters for move events
QMovie	Incremental loading of animations or images, signalling as it progresses
QMutex	Access serialization between threads
QNPInstance	QObject that is a Web-browser plugin
QNPStream	Stream of data provided to a QNPInstance by the browser
QNPWidget	QWidget that is a Web-browser plugin window
QNPlugin	The plugin central factory
QNetworkOperation	Common operations for network protocols
QNetworkProtocol	Common API for network protocols
QObject	The base class of all Qt objects
QObjectCleanupHandler	Watches the lifetime of multiple QObjects
QObjectList	QPtrList of QObjects
QObjectListIt	Iterator for QObjectLists
QPNGImagePacker	Creates well-compressed PNG animations
QPaintDevice	The base class of objects that can be painted
QPaintDeviceMetrics	Information about a paint device
QPaintEvent	Event parameters for paint events
QPainter	Does low-level painting e.g. on widgets
QPair	Value-based template class that provides a pair of elements
QPalette	Color groups for each widget state
QPen	Defines how a QPainter should draw lines and outlines of shapes
QPicture	Paint device that records and replays QPainter commands
QPixmap	Off-screen, pixel-based paint device
QPixmapCache	Application-global cache for pixmaps
QPlatinumStyle	Mac/Platinum look and feel
QPoint	Defines a point in the plane
QPointArray	Array of points
QPopupMenu	Popup menu widget
QPrinter	Paint device that paints on a printer
QProcess	Used to start external programs and to communicate with them
QProgressBar	Horizontal progress bar
QProgressDialog	Feedback on the progress of a slow operation
QPtrCollection	The base class of most pointer-based Qt collections
QPtrDict	Template class that provides a dictionary based on void* keys
QPtrDictIterator	Iterator for QPtrDict collections
QPtrList	Template class that provides doubly-linked lists
QPtrListIterator	Iterator for QPtrList collections
QPtrQueue	Template class that provides a queue
QPtrStack	Template class that provides a stack
QPtrVector	Template collection class that provides a vector (array)
QPushButton	Command button
QRadioButton	Radio button with a text or pixmap label
QRangeControl	Integer value within a range
QRect	Defines a rectangle in the plane
QRegExp	Pattern matching using regular expressions
QRegExpValidator	Used to check a string against a regular expression
QRegion	Clip region for a painter
QResizeEvent	Event parameters for resize events
QSGIStyle	SGI/Irix look and feel
QScreen	And its descendants manage the framebuffer and palette
QScrollBar	Vertical or horizontal scroll bar
QScrollView	Scrolling area with on-demand scroll bars
QSemaphore	Robust integer semaphore
QServerSocket	TCP-based server
QSessionManager	Access to the session manager
QSettings	Persistent platform-independent application settings
QShowEvent	Event which is sent when a widget is shown
QSignal	Can be used to send signals for classes that don't inherit QObject
QSignalMapper	Bundles signals from identifiable senders
QSimpleRichText	Small displayable piece of rich text
QSize	Defines the size of a two-dimensional object
QSizeGrip	Corner-grip for resizing a top-level window
QSizePolicy	Layout attribute describing horizontal and vertical resizing policy
QSjisCodec	Conversion to and from Shift-JIS
QSlider	Vertical or horizontal slider
QSocket	Buffered TCP connection
QSocketDevice	Platform-independent low-level socket API
QSocketNotifier	Support for socket callbacks
QSound	Access to the platform audio facilities
QSpacerItem	Blank space in a layout
QSpinBox	Spin box widget (spin button)
QSplitter	Implements a splitter widget
QSql	Namespace for Qt SQL identifiers that need to be global-like
QSqlCursor	Browsing and editing of SQL tables and views
QSqlDatabase	Used to create SQL database connections and provide transaction handling
QSqlDriver	Abstract base class for accessing SQL databases
QSqlDriverPlugin	Abstract base for custom QSqlDriver plugins
QSqlEditorFactory	Used to create the editors used by QDataTable and QSqlForm
QSqlError	SQL database error information
QSqlField	Manipulates the fields in SQL database tables and views
QSqlFieldInfo	Stores meta data associated with a SQL field
QSqlForm	Creates and manages data entry forms tied to SQL databases
QSqlIndex	Functions to manipulate and describe QSqlCursor and QSqlDatabase indexes
QSqlPropertyMap	Used to map widgets to SQL fields
QSqlQuery	Means of executing and manipulating SQL statements
QSqlRecord	Encapsulates a database record, i.e. a set of database fields
QSqlRecordInfo	Encapsulates a set of database field meta data
QSqlResult	Abstract interface for accessing data from SQL databases
QStatusBar	Horizontal bar suitable for presenting status information
QStoredDrag	Simple stored-value drag object for arbitrary MIME data
QStrIList	Doubly-linked list of char* with case-insensitive comparison
QStrList	Doubly-linked list of char*
QStrListIterator	Iterator for the QStrList and QStrIList classes
QString	Abstraction of Unicode text and the classic C null-terminated char array
QStringList	List of strings
QStyle	The look and feel of a GUI
QStyleFactory	Creates QStyle objects
QStyleOption	Optional parameters for QStyle functions
QStylePlugin	Abstract base for custom QStyle plugins
QStyleSheet	Collection of styles for rich text rendering and a generator of tags
QStyleSheetItem	Encapsulation of a set of text styles
QTab	The structures in a QTabBar
QTabBar	Tab bar, e.g. for use in tabbed dialogs
QTabDialog	Stack of tabbed widgets
QTabWidget	Stack of tabbed widgets
QTable	Flexible editable table widget
QTableItem	The cell content for QTable cells
QTableSelection	Access to a selected area in a QTable
QTabletEvent	Parameters that describe a Tablet event
QTextBrowser	Rich text browser with hypertext navigation
QTextCodec	Conversion between text encodings
QTextCodecPlugin	Abstract base for custom QTextCodec plugins
QTextDecoder	State-based decoder
QTextDrag	Drag and drop object for transferring plain and Unicode text
QTextEdit	Powerful single-page rich text editor
QTextEncoder	State-based encoder
QTextIStream	Convenience class for input streams
QTextOStream	Convenience class for output streams
QTextStream	Basic functions for reading and writing text using a QIODevice
QThread	Platform-independent threads
QTime	Clock time functions
QTimeEdit	Time editor
QTimer	Timer signals and single-shot timers
QTimerEvent	Parameters that describe a timer event
QToolBar	Movable panel containing widgets such as tool buttons
QToolButton	Quick-access button to commands or options, usually used inside a QToolBar
QToolTip	Tool tips (balloon help) for any widget or rectangular part of a widget
QToolTipGroup	Collects tool tips into related groups
QTranslator	Internationalization support for text output
QTranslatorMessage	Translator message and its properties
QTsciiCodec	Conversion to and from the Tamil TSCII encoding
QUriDrag	Drag object for a list of URI references
QUrl	URL parser and simplifies working with URLs
QUrlInfo	Stores information about URLs
QUrlOperator	Common operations on URLs
QVBox	Vertical geometry management of its child widgets
QVBoxLayout	Lines up widgets vertically
QVButtonGroup	Organizes QButton widgets in a vertical column
QVGroupBox	Organizes a group of widgets in a vertical column
QValidator	Validation of input text
QValueList	Value-based template class that provides doubly linked lists
QValueListConstIterator	Const iterator for QValueList
QValueListIterator	Iterator for QValueList
QValueStack	Value-based template class that provides a stack
QValueVector	Value-based template class that provides a dynamic array
QVariant	Acts like a union for the most common Qt data types
QWMatrix	2D transformations of a coordinate system
QWSDecoration	Allows the appearance of the Qt/Embedded Window Manager to be customized
QWSKeyboardHandler	Implements the keyboard driver/handler for Qt/Embedded
QWSMouseHandler	Mouse driver/handler for Qt/Embedded
QWSServer	Server-specific functionality in Qt/Embedded
QWSWindow	Server-specific functionality in Qt/Embedded
QWaitCondition	Allows waiting/waking for conditions between threads
QWhatsThis	Simple description of any widget, i.e. answering the question "What's this?"
QWheelEvent	Parameters that describe a wheel event
QWidget	The base class of all user interface objects
QWidgetFactory	For the dynamic creation of widgets from Qt Designer .ui files
QWidgetItem	Layout item that represents a widget
QWidgetPlugin	Abstract base for custom QWidget plugins
QWidgetStack	Stack of widgets of which only the top widget is user-visible
QWindowsMime	Maps open-standard MIME to Window Clipboard formats
QWindowsStyle	Microsoft Windows-like look and feel
QWizard	Framework for wizard dialogs
QWorkspace	Workspace window that can contain decorated windows, e.g. for MDI
QXmlAttributes	XML attributes
QXmlContentHandler	Interface to report the logical content of XML data
QXmlDTDHandler	Interface to report DTD content of XML data
QXmlDeclHandler	Interface to report declaration content of XML data
QXmlDefaultHandler	Default implementation of all XML handler classes
QXmlEntityResolver	Interface to resolve external entities contained in XML data
QXmlErrorHandler	Interface to report errors in XML data
QXmlInputSource	The input data for the QXmlReader subclasses
QXmlLexicalHandler	Interface to report the lexical content of XML data
QXmlLocator	The XML handler classes with information about the parsing position within a file
QXmlNamespaceSupport	Helper class for XML readers which want to include namespace support
QXmlParseException	Used to report errors with the QXmlErrorHandler interface
QXmlReader	Interface for XML readers (i.e. parsers)
QXmlSimpleReader	Implementation of a simple XML reader (parser)
QXtApplication	Facilitates the mixing of Xt/Motif and Qt widgets
QXtWidget	Allows mixing of Xt/Motif and Qt widgets
Qt	Namespace for miscellaneous identifiers that need to be global-like