HitTest and HitTestXY for wxListBox

This experimental code shows how to implement a working HitTestXY method for wxListBox

{{{
#!python

class MyListBox(wx.ListBox):
    def HitTestXY(self,x,y):
        xs,ys = self.GetClientSize()
        if (y<0) or (x<0) or (x>=xs) or (y>=ys):
            return -1
        index = self.GetScrollPos(wx.VERTICAL) + y/self.GetCharHeight()
        if index >= self.GetCount():
            return -1
        return index
    def HitTest(self,pos):
        return self.HitTestXY(*pos)
}}}