getGraphicalViewer().addDropTargetListener(new YourViewerimpl(getGraphicalViewer()));
/** * Called whenever the User drags over the target. By default, the target Request and * target EditPart are updated, feedback is shown, and auto-expose occurs. */ protected void handleDragOver() { updateTargetRequest(); updateTargetEditPart(); showTargetFeedback(); if (exposeHelper != null) { //If the expose helper does not wish to continue, set helper to null. if (!exposeHelper.step(getDropLocation())) exposeHelper = null; } }