KDE, the largest and oldest Qt based Free and Open Source software community, has just released over 50 Qt5 libraries:
http://kde.org/announcements/kde-frameworks-5.0.php
The libraries are free for usage in both FOSS applications as well as proprietary ones, and provide features ranging from addons to Qt modules, over functional blocks to platform integration and full fledged service based sub systems.
A list, as well as their supported platforms, can be found here
http://api.kde.org/frameworks-api/frameworks5-apidocs/
They are categorized into tiers, where a lower tier means fewer dependencies. A tier 1 framework, for example, does not have any dependencies other than Qt itself.
Cheers,
_
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