moveObjectsToToP，把item移到第一筆
透過event handler，可以使用folder的moveObjectsToTop把某個item移到folder的第一筆，如下範例
def moveContentToTop(obj, event):
"""
Moves Items to the top of its folder
"""
folder = obj.getParentNode()
if folder != None:
folder.moveObjectsToTop(obj.id)