Switch and Checkbox items

[David Edmundson]

Relevant bug report to the discussion:
https://bugs.kde.org/show_bug.cgi?id=302067

I am in favour of any of the proposed solutions.

I think even if we went for option 2, it still makes a lot of sense to
change the existing code for desktop components, just so it's easier
to read. This also allows for fixing anything in the 4.10 timeframe.

Also it's worth still writing into the HIG why this is happening, so
people don't just assume it's a bug. Which in reality means if we go
with option 2, we have to do all 3 anyway.

David