custom 'select' button of subpanel 'sub categories' in module 'product categories'?

In the subpanel ‘sub categories’ In module ‘product cateories’, when ‘select’ is clicked, all categories are shown, including those which are aleady ‘parent’.
If a parent category is selected, the selected parent category will be a child category of the current category. It looks not logical.
Possible to custom the ‘select’ action, only allowing non-parent categories shown on the popup list?