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
public void dragOver(DropTargetEvent event) {
        
        Object target = determineTarget(event);
        
        int oldLocation = currentLocation;
        currentLocation = determineLocation(event);
        setFeedback(event, currentLocation);
        
        if (target != currentTarget || currentLocation != oldLocation) {
            currentTarget = target;
            doDropValidation(event);
        }
    }
    /* (non-Javadoc)
     * Method declared on DropTargetAdapter.
     * The user has dropped something on the desktop viewer.
     */
    public void drop(DropTargetEvent event) {
        currentLocation = determineLocation(event);
        
        if (!performDrop(event.data)) {
            event.detail = DND.DROP_NONE;
        }
        currentOperation = event.detail;
    }
    /* (non-Javadoc)
     * Method declared on DropTargetAdapter.
     * Last chance for the action to disable itself
     */
    public void dropAccept(DropTargetEvent event) {