These classes providing various global services to your application such as event handling, access to system settings, internationalization, etc.
| QClipboard | Access to the window system clipboard |
| QDesktopWidget | Access to screen information on multi-head systems |
| QEvent | The base class of all event classes. Event objects contain event parameters |
| QFontDatabase | Information about the fonts available in the underlying window system |
| QMutex | Access serialization between threads |
| QMutexLocker | Convenience class that simplifies locking and unlocking mutexes |
| QPixmapCache | Application-wide cache for pixmaps |
| QReadLocker | Convenience class that simplifies locking and unlocking read-write locks for read access |
| QReadWriteLock | Read-write locking |
| QSemaphore | General counting semaphore |
| QSessionManager | Access to the session manager |
| QThread | Platform-independent threads |
| QThreadStorage | Per-thread data storage |
| QTranslator | Internationalization support for text output |
| QWaitCondition | Condition variable for synchronizing threads |
| QWriteLocker | Convenience class that simplifies locking and unlocking read-write locks for write access |
