* This was only added because the default tree widget controls don't
render any grid lines. Now that we're custom drawing them, the row
colors are distracting and can be confusing on themes where the
selected row is very faint.
* Since we're promoting everything, we reset the behaviour of
RDTreeWidget so that it's not doing anything different by default.
* RDTreeWidget's interface is a bit different, exposing some useful
things like a single selected item and so on.
* We also can't set columns in the Qt Creator UI anymore, so we set them
from code.
baldurk