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
*
     * @return a <code>DROP_*</code> constant from class <code>DND</code>
     *
     * @see DND#DROP_COPY
     * @see DND#DROP_MOVE
     * @see DND#DROP_LINK
     * @see DND#DROP_NONE
     */
    protected int getCurrentOperation() {
        return currentOperation;
    }
    /**
     * Returns the target object currently under the mouse.
     *
     * @return the current target object
     */
    protected Object getCurrentTarget() {
        return currentTarget;
    }
    /**
     * Returns whether visible insertion feedback should be presented to the user.
     * <p>
     * Typical insertion feedback is the horizontal insertion bars that appear 
     * between adjacent items while dragging.
     * </p>
     *
     * @return <code>true</code> if visual feedback is desired, and <code>false</code> if not
     */
    public boolean getFeedbackEnabled() {
        return feedbackEnabled;