14 DAY TRIAL // Ubuntu developers are really keen on getting the newly released Qt 5.2.1 into Ubunu 14.04 LTS (Trusty Tahr), and it's very likely that they will manage to do it, even if the distribution has entered feature freeze.
The integration of Qt 5.2.1 into the development branch of Ubunu 14.04 LTS (Trusty Tahr) and, subsequently into the stable release, is no small feat. This is important for a lot of reasons, but probably the most notable aspect of this change is the fact that Qt 5.2.1 features a lot of QML fixes, which are straight on Canonical's alley.
If you remember correctly from the announcement made by the Digia developers, Qt 5.2.1 has numerous JavaScript and QML-specific performance optimizations in the new Qt Quick Engine. This translates into a lot less work for the Ubuntu developers.
"The landing is late because it was wanted it wouldn't block other Ubuntu work for uncertain amount of time, and because it was found that Qt 5.2.1 + additional patches upstreamed by Ubuntu developers is the minimum that can be considered to be free enough of regressions. Qt 5.2 saw a complete rewrite of the QML script engine from Google's V8 to Qt's own 'V4' among else, so it's not a big surprise there were hurdles since Ubuntu & Unity 8 are probably one of the heaviest existing Qt5 users," said Canonical's Timo Jyrink in a mailing list post.
Integrating the new Qt 5.2.1 into the Ubuntu 14.04 LTS code base, which is also shared by Ubuntu for phones and Unity, will not magically solve every bug. According to the Ubuntu developers, one of the biggest problems with the old code base was the lack of functional audio and video playback for the camera, but fixes for that particular issue should arrive very soon.
We also mentioned that the Qt 5.2.1 implementation would be done after the feature freeze, which is already in effect.
Feature freeze is a point in the development cycle when it's decided that no new features or packages are uploaded to the repositories. Developers must then focus on fixing the existing problems, improving every aspect as much as possible before the launch.
Some features and packages can receive an exemption from this rule, if they are deemed important enough. Most likely, Qt 5.2.1 will pass that hurdle and will be found in the final version of Ubuntu 14.04 LTS.
Ubuntu 14.04 LTS (Trusty Tahr) is expected to arrive, like clockwork, on April 17, in less than two months.