In the past month, this display manager that's written in Qt's QML has now picked up support for Qt Quick 2 as part of Qt 5.0. QtQuick1/Qt4 is still maintained but now QtQuick2/Qt5 is supported for drawing. Regardless of the Qt release being used by the user, all of the SDDM themes continue to work. SDDM has also picked up support for cursor themes so the default X11 cursor theme is no longer required.
Other SDDM improvements include making the themes more intuitive and usable, a KCM module for integration with the KDE System Settings, and support for configurable themes within the Simple Display Desktop Manager.
For more information on the open-source Linux display manager changes, see this Google+ page or the video that's embedded below of the latest SDDM developments.