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# Window System Specific Notes

Qt is a cross-platform GUI toolkit, so almost the entire API is the same on all platforms and window systems. If you wish to use platform-specific features, and still maintain a platform-independent source tree, you should protect the platform-specific code using the appropriate `#ifdef` directives (see below).

Qt provides a few low-level global functions for fine-tuning applications on specific platforms. See Special-Purpose Global Functions Exported by Qt for details.

- Qt for X11
- Qt for Windows
- Qt for Mac OS X
- Qt for Embedded Linux

For information about which platforms are supported by Qt, see the Platform Notes. For information on distributing Qt applications, see Deploying Qt Applications.

## Qt for X11

When compiling for this platform, the macro `Q_WS_X11` is defined.

Not documented here. Please contact Qt's technical support team if you have queries.

See the Qt for X11 Requirements page for more information about the libraries required to build Qt with as many features as possible.

## Qt for Windows

When compiling for this platform, the macro `Q_WS_WIN` is defined.

Not documented here. Please contact Qt's technical support team if you have queries.

## Qt for Mac OS X

When compiling for this platform, the macro `Q_WS_MAC` is defined.

- Qt for Mac OS X - Specific Issues
- Qt is Mac OS X Native

## Qt for Embedded Linux

When compiling for this platform, the macro `Q_WS_QWS` is defined (the window system is literally the Qt Window System). See the Qt for Embedded Linux documentation for more information.