WxPython。 wx.propgrid。删除属性

Question

有一个属性网格，在网格中有一个类别“ uSignals”：

import wx.propgrid as wxpg

self.pg = wxpg.PropertyGrid(self, size=(500, 600), style=wxpg.PG_SPLITTER_AUTO_CENTER|wxpg.PG_TOOLBAR)

self.uSignals = uSignals = pg.Append(wxpg.PropertyCategory('User signals')) # user signals
self.uSignalsChildren = [] # list of children in the node uSignals

在此类别中，用户添加更多类别：

def AddSignal(self, event):
    newSignal = wxpg.PropertyCategory(self.GenerateSignalName())
    self.pg.AppendIn(self.uSignals, newSignal)
    self.uSignalsChildren.append(newSignal)

用户可以删除添加的属性。写了以下内容（如果有人只知道如何删除一个属性，我将不胜感激）：

def OnDeleteSignal(self, event):
    p = self.pg.GetSelection()
    index = p.GetIndexInParent()
    self.uSignalsChildren.remove(p)
    self.uSignals.DeleteChildren() # remove all nested properties
    # add properties besides deleting (removed it from the list of uSignalsChildren)
    for signal in self.uSignalsChildren:
        self.pg.AppendIn(self.uSignals, signal)

问题：调用OnDeleteSignal时，尝试添加属性（还原不需要删除的属性）时，程序崩溃。 “ python.exe”程序崩溃了。