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
if (!validateDrop(currentTarget, event.detail, event.currentDataType)) {
            event.detail = DND.DROP_NONE;
        }
    }
    /**
     * Returns the bounds of the given SWT tree or table item.
     *
     * @param item the SWT Item
     * @return the bounds, or <code>null</code> if it is not a known type of item
     */
    protected Rectangle getBounds(Item item) {
        if (item instanceof TreeItem) {
            return ((TreeItem) item).getBounds();
        }
        if (item instanceof TableItem) {
            return ((TableItem) item).getBounds(0);
        }
        return null;
    }
    /**
     * Returns a constant describing the position of the mouse relative to the
     * target (before, on, or after the target.  
     *
     * @return one of the <code>LOCATION_* </code> constants defined in this type
     */
    protected int getCurrentLocation() {
        return currentLocation;
    }
    /**
     * Returns the current operation.