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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/X11
- Qt/Windows
- Qt/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/X11

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

Not documented here. Please contact Trolltech Technical Support if you have queries.

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

## Qt/Windows

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

Not documented here. Please contact Trolltech Technical Support if you have queries.

## Qt/Mac OS X

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

- Qt/Mac-Specific Issues
- Qt/Mac 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.