I tried, but the bug wasn't solved. I think, maybe when I removed all roots of tree, then the tree is empty , so occur the bug '0.target is null or...' , is it right? If I'm right, how can I do ? I'v paste my codes to General Discussion, you can write a 'remove' function to try.
http://www.jeasyui.com/forum/index.php?topic=1047.0