wx.grid/wx.grid.GridTableBase can not show data more than 7M rows (with a very simple example)?

Question

The virtual wx.gridtablebase model is known to be able showing infinite rows, but it failed around 7M rows. The following minimal example is tested on wx version:
4.1.2a1.dev5165+64e5d863 msw (phoenix) wxWidgets 3.1.5. Thanks.

import wx
import wx.grid

class GTable(wx.grid.GridTableBase):
    def __init__(self):
        wx.grid.GridTableBase.__init__(self)
        
    def GetNumberRows(self):
        return 10000000

    def GetNumberCols(self):
        return 2

    def GetColLabelValue(self, col):
        return "A"+str(col)
        
    def GetRowLabelValue(self, row):
        return str(row+1)
        
    def IsEmptyCell(self, row, col):
        return False

    def GetValue(self, row, col):
        return str(row)+'-'+str(col)
        
    def SetValue(self, row, col, value):
        pass         

class MyGrid(wx.grid.Grid):
    def __init__(self, parent):
        wx.grid.Grid.__init__(self, parent, -1)
        gtable = GTable()
        self.SetTable(gtable,True)  
        #self.MakeCellVisible(1000000,0)
        #self.AdjustScrollbars()
        #self.ForceRefresh()
        #self.Bind(wx.EVT_SCROLLWIN, self.OnScroll)

class TestFrame(wx.Frame):
    def __init__(self, parent):
        wx.Frame.__init__(self, parent, -1, "A Grid", size=(400, 400))
        grid = MyGrid(self)

if __name__ == '__main__':
    app = wx.App()
    frame=TestFrame(None)
    app.SetTopWindow(frame)
    frame.Show()
    app.MainLoop()