How to prevent the addition of dragged item in tree which drag accepting.?

i have two tree one tree lets say TreeDrag is drag enabled and other is drop enabled lets say TreeDrop.. when i drag item from TreeDrag to TreeDrop,, i want to show feedback and everything开发者_开发问答 else normal except the addition of dragged item in TreeDrop....

Call event.preventDefault() while handling DRAG_DROP event:

private function tree_dragDropHandler(event:DragEvent):void
{
    event.preventDefault();

    tree.hideDropFeedback(event);
    DragManager.showFeedback(DragManager.NONE);
}

This handler should run before Tree's own DRAG_DROP handler, this can be done via adding listener with priority:

tree.addEventListener(DragEvent.DRAG_DROP, tree_dragDropHandler, false, 1);