Bug 29698 drag and drop of java files between packages in package explorer doesn't work
the <preview> <ok> <cancel> dialog shows up, but <ok> has the same effect as <cancel> and <preview> would only show movements of files and no changes in imports of other java files. on <ok> in the preview it only moves the file(s) (as indicated ) without changing referencing imports.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/SelectionTransferDropAdapter.java
private int handleValidateMove(Object target, DropTargetEvent event) throws JavaModelException{
		if (target == null)
			return DND.DROP_NONE;
		
		if (canPasteSourceReferences(target)){
			if (canMoveSelectedSourceReferences(target))
				return DND.DROP_MOVE;
			else	
				return DND.DROP_NONE;
		}	
		
		if (fMoveRefactoring == null){
			fMoveRefactoring= new MoveRefactoring(fElements, JavaPreferencesSettings.getCodeGenerationSettings());
		}	
		
		if (!canMoveElements())
			return DND.DROP_NONE;	
		
		if (fMoveRefactoring.isValidDestination(target))
			return DND.DROP_MOVE;
		else
			return DND.DROP_NONE;	
	}
	
	private boolean canMoveElements() {
		if (fCanMoveElements == 0) {
			fCanMoveElements= 2;
			if (! canActivate(fMoveRefactoring))
				fCanMoveElements= 1;