| Q3Accel | Handles keyboard accelerator and shortcut keys | 
| Q3Action | Abstract user interface action that can appear both in menus and tool bars | 
| Q3ActionGroup | Groups actions together | 
| Q3AsciiCache | Template class that provides a cache based on char* keys | 
| Q3AsciiCacheIterator | Iterator for Q3AsciiCache collections | 
| Q3AsciiDict | Template class that provides a dictionary based on char* keys | 
| Q3AsciiDictIterator | Iterator for Q3AsciiDict collections | 
| Q3Button | Compatibility base class of button widgets | 
| Q3ButtonGroup | Organizes QAbstractButton widgets in a group | 
| Q3CString | Abstraction of the classic C zero-terminated char array (char *) | 
| Q3Cache | Template class that provides a cache based on QString keys | 
| Q3CacheIterator | Iterator for Q3Cache collections | 
| Q3CheckListItem | Checkable list view items | 
| Q3ColorDrag | Drag and drop object for transferring colors between widgets | 
| Q3DateEdit | Date editor | 
| Q3DateTimeEdit | Combines a Q3DateEdit and Q3TimeEdit widget into a single widget for editing datetimes | 
| Q3DateTimeEditBase | Abstraction for date and edit editors | 
| Q3DeepCopy | Template class which ensures that implicitly shared and explicitly shared classes reference unique data | 
| Q3Dict | Template class that provides a dictionary based on QString keys | 
| Q3DictIterator | Iterator for Q3Dict collections | 
| Q3DockArea | Manages and lays out Q3DockWindows | 
| Q3DockWindow | Widget which can be docked inside a Q3DockArea or floated as a top level window on the desktop | 
| Q3DragObject | Encapsulates MIME-based data transfer | 
| Q3DropSite | Nothing and does nothing | 
| Q3FileDialog | Dialogs that allow users to select files or directories | 
| Q3FileIconProvider | Icons for Q3FileDialog to use | 
| Q3FilePreview | File previewing in Q3FileDialog | 
| Q3Frame | 
| Q3Grid | Simple geometry management of its children | 
| Q3GridView | Abstract base for fixed-size grids | 
| Q3GroupBox | Group box frame with a title | 
| Q3HBox | Horizontal geometry management for its child widgets | 
| Q3HButtonGroup | Organizes button widgets in a group with one horizontal row | 
| Q3Header | Header row or column, e.g. for tables and listviews | 
| Q3ImageDrag | Drag and drop object for transferring images | 
| Q3IntCache | Template class that provides a cache based on long keys | 
| Q3IntCacheIterator | Iterator for Q3IntCache collections | 
| Q3IntDict | Template class that provides a dictionary based on long keys | 
| Q3IntDictIterator | Iterator for Q3IntDict collections | 
| Q3ListBox | List of selectable, read-only items | 
| Q3ListBoxItem | The base class of all list box items | 
| Q3ListBoxPixmap | List box items with a pixmap and optional text | 
| Q3ListBoxText | List box items that display text | 
| Q3ListView | Implements a list/tree view | 
| Q3ListViewItem | Implements a list view item | 
| Q3ListViewItemIterator | Iterator for collections of Q3ListViewItems | 
| Q3LocalFs | Implementation of a QNetworkProtocol that works on the local file system | 
| Q3MainWindow | Main application window, with a menu bar, dock windows (e.g. for toolbars), and a status bar | 
| Q3MemArray | Template class that provides arrays of simple types | 
| Q3MimeSourceFactory | Extensible provider of mime-typed data | 
| Q3MultiLineEdit | Simple editor for inputting text | 
| Q3NetworkOperation | Common operations for network protocols | 
| Q3NetworkProtocol | Common API for network protocols | 
| Q3PaintDeviceMetrics | Information about a paint device | 
| Q3Painter | Qt 3 compatibility wrapper for QPainter | 
| Q3Picture | Paint device that records and replays Q3Painter commands | 
| Q3PointArray | 
| Q3PopupMenu | Thin compatibility wrapper around QMenu | 
| Q3Process | Used to start external programs and to communicate with them | 
| Q3ProgressBar | Horizontal progress bar | 
| Q3ProgressDialog | Feedback on the progress of a slow operation | 
| Q3PtrCollection | The base class of most pointer-based Qt collections | 
| Q3PtrDict | Template class that provides a dictionary based on void* keys | 
| Q3PtrDictIterator | Iterator for Q3PtrDict collections | 
| Q3PtrList | Template class that provides a list | 
| Q3PtrListIterator | Iterator for Q3PtrList collections | 
| Q3PtrQueue | Template class that provides a queue | 
| Q3PtrStack | Template class that provides a stack | 
| Q3PtrVector | Template collection class that provides a vector (array) | 
| Q3RangeControl | Integer value within a range | 
| Q3ScrollView | Scrolling area with on-demand scroll bars | 
| Q3Semaphore | Robust integer semaphore | 
| Q3Shared | Used internally for implementing shared classes | 
| Q3Signal | Can be used to send signals for classes that don't inherit QObject | 
| Q3SimpleRichText | Small displayable piece of rich text | 
| Q3StoredDrag | Simple stored-value drag object for arbitrary MIME data | 
| Q3StrIList | Doubly-linked list of char* with case-insensitive comparison | 
| Q3StrList | Doubly-linked list of char* | 
| Q3StrListIterator | Iterator for the Q3StrList and Q3StrIList classes | 
| Q3StyleSheet | Collection of styles for rich text rendering and a generator of tags | 
| Q3StyleSheetItem | Encapsulation of a set of text styles | 
| Q3SyntaxHighlighter | Base class for implementing Q3TextEdit syntax highlighters | 
| Q3TabDialog | Stack of tabbed widgets | 
| Q3TextBrowser | Rich text browser with hypertext navigation | 
| Q3TextDrag | Drag and drop object for transferring plain and Unicode text | 
| Q3TextEdit | Powerful single-page rich text editor | 
| Q3TextView | Rich text viewer | 
| Q3TimeEdit | Time editor | 
| Q3ToolBar | Movable panel containing widgets such as tool buttons | 
| Q3UriDrag | Drag object for a list of URI references | 
| Q3Url | URL parser and simplifies working with URLs | 
| Q3UrlOperator | Common operations on URLs | 
| Q3VBox | Vertical geometry management of its child widgets | 
| Q3VButtonGroup | Organizes button widgets in a vertical column | 
| Q3ValueList | Value-based template class that provides lists | 
| Q3ValueListConstIterator | Const iterator for Q3ValueList | 
| Q3ValueListIterator | Iterator for Q3ValueList | 
| Q3ValueStack | Value-based template class that provides a stack | 
| Q3ValueVector | Value-based template class that provides a dynamic array | 
| Q3WhatsThis | 
| Q3WidgetStack | Stack of widgets of which only the top widget is user-visible | 
| Q3Wizard | Framework for wizard dialogs | 
| QAbstractButton | The abstract base class of button widgets, providing functionality common to buttons | 
| QAbstractEventDispatcher | Manages Qt's event queue, excluding GUI-related events | 
| QAbstractItemDelegate | Used to display and edit data items from a model | 
| QAbstractItemModel | The abstract interface for item model classes | 
| QAbstractItemView | The basic functionality for item view classes | 
| QAbstractListModel | Abstract model that can be subclassed to create one-dimensional list models | 
| QAbstractPrintDialog | Base implementation for print dialogs used to configure printers | 
| QAbstractScrollArea | Scrolling area with on-demand scroll bars | 
| QAbstractSlider | Integer value within a range | 
| QAbstractSpinBox | Spinbox and a line edit to display values | 
| QAbstractTableModel | Abstract model that can be subclassed to create table models | 
| QAbstractTextDocumentLayout | Abstract base class used to implement custom layouts for QTextDocuments | 
| QAccessible | Enums and static functions relating to accessibility | 
| QAccessibleBridge | The base class for accessibility back-ends | 
| QAccessibleBridgePlugin | Abstract base for accessibility bridge plugins | 
| QAccessibleEvent | Used to query addition accessibility information about complex widgets | 
| QAccessibleInterface | Defines an interface that exposes information about accessible objects | 
| QAccessibleObject | Implements parts of the QAccessibleInterface for QObjects | 
| QAccessiblePlugin | Abstract base for accessibility plugins | 
| QAccessibleWidget | Implements the QAccessibleInterface for QWidgets | 
| QAction | Abstract user interface action that can be inserted into widgets | 
| QActionEvent | Event that is generated when a QAction is added, removed, or changed | 
| QActionGroup | Groups actions together | 
| QApplication | Manages the GUI application's control flow and main settings | 
| QBasicTimer | Timer events for objects | 
| QBitArray | Array of bits | 
| 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 | QIODevice interface for a QByteArray | 
| QButtonGroup | Container to organize groups of button widgets | 
| QByteArray | Array of bytes | 
| QByteArrayMatcher | Holds a sequence of bytes that can be quickly matched in a byte array | 
| QCDEStyle | CDE look and feel | 
| QCache | Template class that provides a cache | 
| QChar | 16-bit Unicode character | 
| QCheckBox | Checkbox with a text label | 
| 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 | 
| QColorGroup | 
| QColormap | Maps device independent QColors to device dependent pixel values | 
| QComboBox | Combined button and popup list | 
| QCommonStyle | Encapsulates the common Look and Feel of a GUI | 
| QConicalGradient | Used in combination with QBrush to specify a conical gradient brush | 
| QContextMenuEvent | Parameters that describe a context menu event | 
| QCopChannel | Communication capabilities between several clients | 
| QCoreApplication | Event loop for console Qt applications | 
| QCursor | Mouse cursor with an arbitrary shape | 
| QCustomEvent | Support for custom events | 
| QDataStream | Serialization of binary data to a QIODevice | 
| QDate | Date functions | 
| QDateEdit | Widget for editing dates based on the QDateTimeEdit widget | 
| QDateTime | Date and time functions | 
| QDateTimeEdit | Widget for editing dates and times | 
| QDecoration | Allows the appearance of the Qt/Embedded Window Manager to be customized | 
| QDecorationFactory | Creates QDecoration objects | 
| QDecorationPlugin | Abstract base for custom QDecoration plugins | 
| 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 | 
| QDir | Access to directory structures and their contents | 
| QDirModel | Data model for the local filesystem | 
| QDirectPainter | Direct access to the video hardware | 
| QDockWidget | Widget that can be docked inside a QMainWindow or floated as a top-level window on the desktop | 
| QDoubleSpinBox | Spin box widget that takes doubles | 
| QDoubleValidator | Range checking of floating-point numbers | 
| QDrag | Support for MIME-based drag and drop data transfer | 
| QDragEnterEvent | Event which is sent to a widget when a drag and drop action enters it | 
| QDragLeaveEvent | Event that is sent to a widget when a drag and drop action leaves it | 
| QDragMoveEvent | Event which is sent while a drag and drop action is in progress | 
| QDropEvent | Event which is sent when a drag and drop action is completed | 
| QErrorMessage | Error message display dialog | 
| QEvent | The base class of all event classes. Event objects contain event parameters | 
| QEventLoop | Means of entering and leaving an event loop | 
| QFile | Interface for reading from and writing to files | 
| QFileDialog | Dialog that allow users to select files or directories | 
| QFileIconProvider | File icon for the QDirModel class | 
| QFileInfo | System-independent file information | 
| QFileOpenEvent | Event that will be sent when there is a request to open a file | 
| QFlag | Helper data type for QFlags | 
| QFlags | Type-safe way of storing OR-combinations of enum values | 
| QFocusEvent | Event parameters for widget focus events | 
| QFocusFrame | Focus frame which can be outside of a widget's normal paintable area | 
| 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 | 
| QFontMetrics | Font metrics information | 
| QFontMetricsF | Font metrics information | 
| QFrame | The base class of widgets that can have a frame | 
| QGenericArgument | Internal helper class for marshalling arguments | 
| QGenericReturnArgument | Internal helper class for marshalling arguments | 
| QGradient | Used in combination with QBrush to specify gradient fills | 
| QGridLayout | Lays out widgets in a grid | 
| QGroupBox | Group box frame with a title | 
| QHBoxLayout | Lines up widgets horizontally | 
| QHash | Template class that provides a hash-table-based dictionary | 
| QHashIterator | Java-style const iterator for QHash and QMultiHash | 
| QHeaderView | Header row or header column for item views | 
| QHelpEvent | Event that is used to request helpful information about a particular point in a widget | 
| QHideEvent | Event which is sent after a widget is hidden | 
| QHoverEvent | Parameters that describe a mouse event | 
| QIODevice | The base interface class of all I/O devices in Qt | 
| QIcon | Scalable icons in different modes and states | 
| QIconDragEvent | Indicates that a main icon drag has begun | 
| QIconEngine | Abstract base class for QIcon renderers | 
| QIconEnginePlugin | Abstract base for custom QIconEngine plugins | 
| QImage | Hardware-independent pixmap that allows direct access to the pixel data, and can be used as a paint device | 
| QImageIOHandler | Defines the common image I/O interface for all image formats in Qt | 
| QImageIOPlugin | Defines an interface for writing an image format plugin | 
| QImageReader | Format independent interface for reading images from files or other devices | 
| QImageWriter | Format independent interface for writing images to files or other devices | 
| QInputContext | Abstracts the input method dependent data and composing state | 
| QInputContextFactory | Creates QInputContext objects | 
| QInputContextPlugin | Abstract base for custom QInputContext plugins | 
| QInputDialog | Simple convenience dialog to get a single value from the user | 
| QInputEvent | The base class for events that describe user input | 
| QInputMethodEvent | Parameters for input method events | 
| QIntValidator | Validator that ensures a string contains a valid integer within a specified range | 
| QItemDelegate | Display and editing facilities for data items from a model | 
| QItemEditorCreatorBase | Abstract base class that must be subclassed when implementing new item editor creators | 
| QItemEditorFactory | Widgets for editing item data in views and delegates | 
| QItemSelection | Manages information about selected items in a model | 
| QItemSelectionModel | Keeps track of a view's selected items | 
| QItemSelectionRange | Manages information about a range of selected items in a model | 
| QKbdDriverFactory | Creates QWSKeyboardHandler objects for Qt/Embedded | 
| QKbdDriverPlugin | Abstract base for Qt/Embedded keyboard driver plugins | 
| QKeyEvent | Describes a key event | 
| QKeySequence | Encapsulates a key sequence as used by shortcuts | 
| QLCDNumber | Displays a number with LCD-like digits | 
| QLabel | Text or image display | 
| QLatin1Char | 8-bit ASCII/Latin-1 character | 
| QLatin1String | Thin wrapper around an ASCII/Latin-1 encoded string literal | 
| QLayout | The base class of geometry managers | 
| QLayoutItem | Abstract item that a QLayout manipulates | 
| QLibrary | Loads shared libraries at runtime | 
| QLibraryInfo | Information about the Qt library | 
| QLine | Two-dimensional vector that uses integer point accuracy for coordinates | 
| QLineEdit | One-line text editor | 
| QLineF | Two-dimensional vector that uses floating point accuracy for coordinates | 
| QLinearGradient | Used in combination with QBrush to specify a linear gradient brush | 
| QLinkedList | Template class that provides linked lists | 
| QLinkedListIterator | Java-style const iterator for QLinkedList | 
| QList | Template class that provides lists | 
| QListIterator | Java-style const iterator for QList and QQueue | 
| QListView | List or icon view onto a model | 
| QListWidget | Item-based list widget | 
| QListWidgetItem | Item for use with the QListWidget item view class | 
| QLocale | Converts between numbers and their string representations in various languages | 
| QMacMime | Maps open-standard MIME to Mac flavors | 
| QMacStyle | Implements an Appearance Manager style | 
| QMainWindow | Main application window | 
| QMap | Template class that provides a skip-list-based dictionary | 
| QMapIterator | Java-style const iterator for QMap and QMultiMap | 
| QMatrix | 2D transformations of a coordinate system | 
| QMenu | Menu widget for use in menu bars, context menus, and other popup menus | 
| QMenuBar | Horizontal menu bar | 
| QMenuItem | Represents an item in a menu | 
| QMessageBox | Modal dialog with a short message, an icon, and some buttons | 
| QMetaClassInfo | Additional information about a class | 
| QMetaEnum | Meta-data about an enumerator | 
| QMetaMethod | Meta-data about a member function | 
| QMetaObject | Meta-information about Qt objects | 
| QMetaProperty | Meta-data about a property | 
| QMetaType | Manages named types in the meta object system | 
| QMimeData | Container for data that records information about its MIME type | 
| QMimeSource | Abstraction of objects that provided formatted data of a certain MIME type | 
| QModelIndex | Used to locate data in a data model | 
| QMotifStyle | Motif look and feel | 
| QMouseDriverFactory | Creates QWSMouseHandler objects for Qt/Embedded | 
| QMouseDriverPlugin | Abstract base for Qt/Embedded mouse driver plugins | 
| QMouseEvent | Parameters that describe a mouse event | 
| QMoveEvent | Event parameters for move events | 
| QMovie | Convenience class for playing movies with QImageReader | 
| QMultiHash | Convenience QHash subclass that provides multi-valued hashes | 
| QMultiMap | Convenience QMap subclass that provides multi-valued maps | 
| QMutableHashIterator | Java-style non-const iterator for QHash and QMultiHash | 
| QMutableLinkedListIterator | Java-style non-const iterator for QLinkedList | 
| QMutableListIterator | Java-style non-const iterator for QList and QQueue | 
| QMutableMapIterator | Java-style non-const iterator for QMap and QMultiMap | 
| QMutableVectorIterator | Java-style non-const iterator for QVector and QStack | 
| QMutex | Access serialization between threads | 
| QMutexLocker | Convenience class that simplifies locking and unlocking mutexes | 
| QObject | The base class of all Qt objects | 
| QObjectCleanupHandler | Watches the lifetime of multiple QObjects | 
| QPageSetupDialog | Configuration dialog for the page-related options on a printer | 
| QPaintDevice | The base class of objects that can be painted | 
| QPaintEngine | Abstract definition of how QPainter draws to a given device on a given platform | 
| QPaintEvent | Event parameters for paint events | 
| QPainter | Performs low-level painting on widgets and other paint devices | 
| QPainterPath | Container for painting operations, enabling graphical shapes to be constructed and reused | 
| QPair | Template class that stores a pair of items | 
| QPalette | Color groups for each widget state | 
| QPen | Defines how a QPainter should draw lines and outlines of shapes | 
| QPersistentModelIndex | Used to locate data in a data model | 
| QPicture | Paint device that records and replays QPainter commands | 
| QPictureFormatPlugin | Abstract base for custom picture format plugins | 
| QPictureIO | Parameters for loading and saving pictures | 
| QPixmap | Off-screen, pixel-based paint device | 
| QPixmapCache | Application-wide cache for pixmaps | 
| QPlastiqueStyle | Widget style similar to the Plastik style available in KDE | 
| QPluginLoader | Loads a plugin at run-time | 
| QPoint | Defines a point in the plane | 
| QPointF | Point object that uses floating point coordinates for accuracy | 
| QPointer | Template class that provides guarded pointers to QObjects | 
| QPolygon | Vector of points | 
| QPolygonF | Vector of floating point points | 
| QPrintDialog | Dialog for specifying the printer's configuration | 
| QPrintEngine | Defines an interface for how QPrinter interacts with a given printing subsystem | 
| 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 | 
| QProxyModel | Support for filtering and sorting data that is passed between another model and a view | 
| QPushButton | Command button | 
| QQueue | Generic container that provides a queue | 
| QRadialGradient | Used in combination with QBrush to specify a radial gradient brush | 
| QRadioButton | Radio button with a text label | 
| QReadLocker | Convenience class that simplifies locking and unlocking read-write locks for read access | 
| QReadWriteLock | Read-write locking | 
| QRect | Defines a rectangle in the plane that uses integer point accuracy for coordinates | 
| QRectF | Defines a rectangle in the plane using floating point coordinates for accuracy | 
| 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 | 
| QRubberBand | Rectangle or line that can indicate a selection or a boundary | 
| QScreen | And its descendants manage the framebuffer and palette | 
| QScreenDriverFactory | Creates QScreen objects for Qt/Embedded | 
| QScreenDriverPlugin | Abstract base for Qt/Embedded graphics driver plugins | 
| QScrollArea | Scrolling view onto another widget | 
| QScrollBar | Vertical or horizontal scroll bar | 
| QSemaphore | General counting semaphore | 
| QSessionManager | Access to the session manager | 
| QSet | Template class that provides a hash-table-based set | 
| QSetIterator | Java-style const iterator for QSet | 
| QSettings | Persistent platform-independent application settings | 
| QSharedData | Base class for shared data objects | 
| QSharedDataPointer | Pointer to a shared data object | 
| QShortcut | Used to create keyboard shortcuts | 
| QShortcutEvent | Event which is generated when the user presses a key combination | 
| QShowEvent | Event that is sent when a widget is shown | 
| QSignalMapper | Bundles signals from identifiable senders | 
| QSize | Defines the size of a two-dimensional object | 
| QSizeF | Defines the size of a two-dimensional object using floating point values for accuracy | 
| QSizeGrip | Corner-grip for resizing a top-level window | 
| QSizePolicy | Layout attribute describing horizontal and vertical resizing policy | 
| QSlider | Vertical or horizontal slider | 
| QSocketNotifier | Support for monitoring activity on a file descriptor | 
| QSound | Access to the platform audio facilities | 
| QSpacerItem | Blank space in a layout | 
| QSpinBox | Spin box widget | 
| QSplashScreen | Splash screen that can be shown during application startup | 
| QSplitter | Implements a splitter widget | 
| QSplitterHandle | Handle functionality of the splitter | 
| QStack | Template class that provides a stack | 
| QStackedLayout | Stack of widgets where only one widget is visible at a time | 
| QStackedWidget | Stack of widgets where only one widget is visible at a time | 
| QStandardItemModel | Generic model for storing custom data | 
| QStatusBar | Horizontal bar suitable for presenting status information | 
| QStatusTipEvent | Event that is used to show messages in a status bar | 
| QString | Unicode character string | 
| QStringList | List of strings | 
| QStringListModel | Model that supplies strings to views | 
| QStringMatcher | Holds a sequence of characters that can be quickly matched in a Unicode string | 
| QStyle | Abstract base class that encapsulates the look and feel of a GUI | 
| QStyleFactory | Creates QStyle objects | 
| QStyleHintReturn | Style hints that return more than basic data types | 
| QStyleHintReturnMask | Style hints that return a QRegion | 
| QStyleOption | Stores the parameters used by QStyle functions | 
| QStyleOptionButton | Used to describe the parameters for drawing buttons | 
| QStyleOptionComboBox | Used to describe the parameter for drawing a combobox | 
| QStyleOptionComplex | Used to hold parameters that are common to all complex controls | 
| QStyleOptionDockWidget | Used to describe the parameters for drawing a dock window | 
| QStyleOptionFocusRect | Used to describe the parameters for drawing a focus rectangle with QStyle | 
| QStyleOptionFrame | Used to describe the parameters for drawing a frame | 
| QStyleOptionHeader | Used to describe the parameters for drawing a header | 
| QStyleOptionMenuItem | Used to describe the parameter necessary for drawing a menu item | 
| QStyleOptionProgressBar | Used to describe the parameters necessary for drawing a progress bar | 
| QStyleOptionQ3DockWindow | Used to describe the parameters for drawing various parts of a  | 
| QStyleOptionQ3ListView | Used to describe the parameters for drawing a Q3ListView | 
| QStyleOptionQ3ListViewItem | Used to describe an item drawn in a Q3ListView | 
| QStyleOptionRubberBand | Used to describe the parameters needed for drawing a rubber band | 
| QStyleOptionSlider | Used to describe the parameters needed for drawing a slider | 
| QStyleOptionSpinBox | Used to describe the parameters necessary for drawing a spin box | 
| QStyleOptionTab | Used to describe the parameters for drawing a tab bar | 
| QStyleOptionTabWidgetFrame | Used to describe the parameters for drawing the frame around a tab widget | 
| QStyleOptionTitleBar | Used to describe the parameters for drawing a title bar | 
| QStyleOptionToolBox | Used to describe the parameters needed for drawing a tool box | 
| QStyleOptionToolButton | Used to describe the parameters for drawing a tool button | 
| QStyleOptionViewItem | Used to describe the parameters used to draw an item in a view widget | 
| QStylePainter | Convenience class for drawing QStyle elements inside a widget | 
| QStylePlugin | Abstract base for custom QStyle plugins | 
| QSysInfo | Information about the system | 
| QTabBar | Tab bar, e.g. for use in tabbed dialogs | 
| QTabWidget | Stack of tabbed widgets | 
| QTableView | Default model/view implementation of a table view | 
| QTableWidget | Item-based table view with a default model | 
| QTableWidgetItem | Item for use with the QTableWidget class | 
| QTableWidgetSelectionRange | Container for storing a selection range in a QTableWidget | 
| QTabletEvent | Parameters that describe a Tablet event | 
| QTemporaryFile | I/O device that operates on temporary files | 
| QTextBlock | Container for text fragments in a QTextDocument | 
| QTextBlockFormat | Formatting information for blocks of text in a QTextDocument | 
| QTextBlockGroup | Container for text blocks within a QTextDocument | 
| QTextBrowser | Rich text browser with hypertext navigation | 
| QTextCharFormat | Formatting information for characters in a QTextDocument | 
| QTextCodec | Conversions between text encodings | 
| QTextCodecPlugin | Abstract base for custom QTextCodec plugins | 
| QTextCursor | Offers an API to access and modify QTextDocuments | 
| QTextDecoder | State-based decoder | 
| QTextDocument | Holds formatted text that can be viewed and edited using a QTextEdit | 
| QTextDocumentFragment | Represents a piece of formatted text from a QTextDocument | 
| QTextEdit | Widget that is used to edit and display both plain and rich text | 
| QTextEncoder | State-based encoder | 
| QTextFormat | Formatting information for a QTextDocument | 
| QTextFragment | Holds a piece of text in a QTextDocument with a single QTextCharFormat | 
| QTextFrame | Represents a frame in a QTextDocument | 
| QTextFrameFormat | Formatting information for frames in a QTextDocument | 
| QTextIStream | Convenience class for input streams | 
| QTextImageFormat | Formatting information for images in a QTextDocument | 
| QTextInlineObject | Represents an inline object in a QTextLayout | 
| QTextLayout | Used to lay out and paint a single paragraph of text | 
| QTextLength | Encapsulates the different types of length used in a QTextDocument | 
| QTextLine | Represents a line of text inside a QTextLayout | 
| QTextList | Decorated list of items in a QTextDocument | 
| QTextListFormat | Formatting information for lists in a QTextDocument | 
| QTextOStream | Convenience class for output streams | 
| QTextObject | Base class for different kinds of objects that can group parts of a QTextDocument together | 
| QTextOption | Description of general rich text properties | 
| QTextStream | Convenient interface for reading and writing text | 
| QTextTable | Represents a table in a QTextDocument | 
| QTextTableCell | Represents the properties of a cell in a QTextTable | 
| QTextTableFormat | Formatting information for tables in a QTextDocument | 
| QThread | Platform-independent threads | 
| QThreadStorage | Per-thread data storage | 
| QTime | Clock time functions | 
| QTimeEdit | Widget for editing times based on the QDateTimeEdit widget | 
| QTimer | Repetitive and single-shot timers | 
| QTimerEvent | Parameters that describe a timer event | 
| QToolBar | Movable panel that contains a set of controls | 
| QToolBox | Column of tabbed widget items | 
| QToolButton | Quick-access button to commands or options, usually used inside a QToolBar | 
| QToolTip | Tool tips (balloon help) for any widget | 
| QTranslator | Internationalization support for text output | 
| QTreeView | Default model/view implementation of a tree view | 
| QTreeWidget | Tree view that uses a predefined tree model | 
| QTreeWidgetItem | Item for use with the QTreeWidget convenience class | 
| QUrl | Convenient interface for working with URLs | 
| QUuid | Stores a Universally Unique Identifier (UUID) | 
| QVBoxLayout | Lines up widgets vertically | 
| QValidator | Validation of input text | 
| QVarLengthArray | Low-level variable-length array | 
| QVariant | Acts like a union for the most common Qt data types | 
| QVector | Template class that provides a dynamic array | 
| QVectorIterator | Java-style const iterator for QVector and QStack | 
| QWSInputMethod | International input methods for Qt/Embedded | 
| QWSKeyboardHandler | Implements the keyboard driver for Qt/Embedded | 
| QWSMouseHandler | Mouse driver for Qt/Embedded | 
| QWSServer | Server-specific functionality in Qt/Embedded | 
| QWSWindow | Server-specific functionality in Qt/Embedded | 
| QWaitCondition | Condition variable for synchronizing threads | 
| QWhatsThis | Simple description of any widget, i.e. answering the question "What's This?" | 
| QWhatsThisClickedEvent | Event that can be used to handle hyperlinks in a "What's This?" text | 
| QWheelEvent | Parameters that describe a wheel event | 
| QWidget | The base class of all user interface objects | 
| QWidgetItem | Layout item that represents a widget | 
| QWindowStateChangeEvent | The window state before a window state change | 
| QWindowsMime | Maps open-standard MIME to Window Clipboard formats | 
| QWindowsStyle | Microsoft Windows-like look and feel | 
| QWindowsXPStyle | Microsoft WindowsXP-like look and feel | 
| QWorkspace | Workspace window that be used in an MDI application | 
| QWriteLocker | Convenience class that simplifies locking and unlocking read-write locks for write access | 
| QX11EmbedContainer | XEmbed container widget | 
| QX11EmbedWidget | XEmbed client widget | 
| QX11Info | Information about the X display configuration |