Z:gnu-www-ja-selling-exceptions--681dd9-The KDE desktop was developed/en

The KDE desktop was developed in the 90s based on the Qt library. Qt was proprietary software, and TrollTech charged for permission to embed it in proprietary applications. TrollTech allowed gratis use of Qt in free applications, but this did not make it free/libre software. Completely free operating systems therefore could not include Qt, so they could not use KDE either.