Gtk3, as I stated elsewhere, has some changes which cater better for tablets so that should automatically drop some of the required changes. I'd really like to see Gtk3 and Qt5 as the main toolkits, or even just Qt5 if using a ported version of qildon.

I've been looking into required changes for hildon-components and they seem to be pretty straight forward. Replace declarative module with qml, rename included headers and so forth. Only big deal is if anything needs to use new scene graph from what I've read up on.
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Have you had any luck with underlying components, if needed/worthwhile like bme, mce? Might simplify some of the scripts we've had posted so far.