Bug 63155 [Refactoring] no user feedback when error during implicit refactoring triggered by drag'n'drop
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/SelectionTransferDropAdapter.java
if (fMoveProcessor == null) {
			IResource[] resources= ReorgUtils.getResources(fElements);
			IJavaElement[] javaElements= ReorgUtils.getJavaElements(fElements);
			fMoveProcessor= JavaMoveProcessor.create(resources, javaElements, JavaPreferencesSettings.getCodeGenerationSettings());
		}
		
		if (!canMoveElements())
			return DND.DROP_NONE;	
		if (target instanceof IResource && fMoveProcessor != null && fMoveProcessor.setDestination((IResource)target).isOK())
			return DND.DROP_MOVE;
		else if (target instanceof IJavaElement && fMoveProcessor != null && fMoveProcessor.setDestination((IJavaElement)target).isOK())
			return DND.DROP_MOVE;
		else
			return DND.DROP_NONE;	
	}
	
	private boolean canMoveElements() {
		if (fCanMoveElements == 0) {
			fCanMoveElements= 2;
			if (fMoveProcessor == null)
				fCanMoveElements= 1;
		}
		return fCanMoveElements == 2;
	}
	
	private void handleDropLink(Object target, DropTargetEvent event) {
		if (fAddMethodStubAction.init((IType)target, getSelection())) 
			fAddMethodStubAction.run();
	}