Jolla's Sailfish, Canonical's recently announced Ubuntu Phone, and KDE's Plasma Active environments are all using Qt5's QML for interface design. Unfortunately, the set of UI components provided by each, although similar, are incompatible with the others. After a chat on IRC between developers of all three platforms, they've decided to discuss the reasons behind each implementation, in the hopes that they can work toward a common architecture.
"There are also discussions underway regarding other aspects of the bigger puzzle such as common package formats and delivery strategies. We are poised, should we keep our heads straight and our feet moving, to evolve that holiest of grails in the mobile space: an open and vendor neutral application development strategy built around the commonality of QtQuick and Linux. This is our Rome, which will not be built in a day, but which can become something significant in the world if we keep our heads and follow through."