Steps to Reproduce:

1. run attached zul
2. move down "Item 1", selection status is kept
3. move up "Item 3"

Actual:

selection status is lost

Expected:

selection status is kept

Extra Information

Server selection status is correct, you can check it y tree1.getSelectedItem(). only client side rendering is wrong.

Workaround

clear and add selection again after moving an item, e.g.

public void moveUp(){
    //move up an item
    tree1.clearSelection();
    tree1.selectItem(item);
}