Bug 72297 [DnD] ViewerDropAdapter impossible to set DND.FEEDBACK_NONE
It is not possible to disable selection feedback in ViewerDropAdapter. There are setFeedbackEnabled(false) and setScrollExpandEnabled(false) methods to turn off the feedback effects. If those methods are used, selection feedback still provided. It is not possible to turn it off, elements are still selected when drag is over them. Overriding method; private void setFeedback(DropTargetEvent event, int location) { event.feedback = DND.FEEDBACK_NONE; } - does not chenge the feedback either. setFeedbackEnabled() should be extended to disable SELECTION feedback or new method created, setSelectionFeedback().
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerDropAdapter.java
private boolean scrollExpandEnabled = true;
    /**
     * Creates a new drop adapter for the given viewer.
     *
     * @param viewer the viewer
     */
    protected ViewerDropAdapter(Viewer viewer) {
        this.viewer = viewer;
    }
    /**
     * Returns the position of the given event's coordinates relative to its target.
     * The position is determined to be before, after, or on the item, based on
     * some threshold value.
     *
     * @param event the event
     * @return one of the <code>LOCATION_* </code>constants defined in this class
     */
    protected int determineLocation(DropTargetEvent event) {
        if (!(event.item instanceof Item)) {
            return LOCATION_NONE;
        }
        Item item = (Item) event.item;
        Point coordinates = new Point(event.x, event.y);
        coordinates = viewer.getControl().toControl(coordinates);
        if (item != null) {
            Rectangle bounds = getBounds(item);
            if (bounds == null) {
                return LOCATION_NONE;
            }
            if ((coordinates.y - bounds.y) < 5) {