Code review comment for lp://qastaging/~osomon/unity-2d/dnd2

I understand now why it's "perceivably slow". In LauncherView::launcherItemAt you go through the whole scenegraph for _every_ move of the mouse. That is absolutely not acceptable.

I do not understand why the plan has changed:
LauncherView should not know about the list of LauncherItems at all. The LauncherItem should take care of their own drag&drop events, not only the actions on drop but also the detection of the drag. Why are not we creating a QML item that is able to do that similar to what is done in:

https://bitbucket.org/gregschlom/qml-drag-drop/src/e5dbe26c3073/DeclarativeDropArea.cpp

It would be less code, faster and also above all it will allow much greater flexibility.