In some cases, it isn't possible to find equivalent behavior or user interface elements on every platform your application or toolkit supports. In these cases, you may find the toolkit providing operating system-specific extensions that can be used in your application code. If you make use of these platform-specific items, you'll need to ensure that your code still functions correctly on other target systems. This would normally be handled by the build constraints such as the preceding, where some implementations may have no or reduced functionality to match the lowest common denominator.

Such a platform extension is Qt Windows Extras, which provides the taskbar icon progress API and a method for providing a jump list (a set of shortcuts from the application icon). This project can be found at http://doc.qt.io/qt-5/qtwinextras-index.html.