Bug 29711 Move refactoring doesn't honor read-only flags
Build I20030115 - JUnit setup - create TestCase.java in junit.runner - make it read-only - move TestCase from framework to runner - answer yes to override observe: the file in runner gets replaced althouh it is read-only
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/SelectionTransferDropAdapter.java
public void validateDrop(Object target, DropTargetEvent event, int operation) {
		event.detail= DND.DROP_NONE;
		
		if (tooFast(event)) 
			return;
		
		initializeSelection();
				
		try {
			if (operation == DND.DROP_DEFAULT) {
				event.detail= handleValidateDefault(target, event);
			} else if (operation == DND.DROP_COPY) {
				event.detail= handleValidateCopy(target, event);
			} else if (operation == DND.DROP_MOVE) {
				event.detail= handleValidateMove(target, event);
			} else if (operation == DND.DROP_LINK) {
				event.detail= handleValidateLink(target, event);
			}
		} catch (JavaModelException e){
			ExceptionHandler.handle(e, PackagesMessages.getString("SelectionTransferDropAdapter.error.title"), PackagesMessages.getString("SelectionTransferDropAdapter.error.message")); 
			event.detail= DND.DROP_NONE;
		}	
	}
	protected void initializeSelection(){
		if (fElements != null)
			return;
		ISelection s= LocalSelectionTransfer.getInstance().getSelection();
		if (!(s instanceof IStructuredSelection))
			return;