Bug 232777 [Viewers] ViewerDropAdapter holds currentTarget forever
Build ID: 3.3.2 Member currentTarget should be set to null after drop or after cancel, because it holds a domain object, which can't be garbage collected after Viewer.setInput(null).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerDropAdapter.java
}
    /**
     * 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.
     *
     * @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;