Noticed a recursive call on listbox select

[infiniteTesch]

I've added this code to overcome it:

def on_listbox_select(self, selected_option):
    self.counter += 1
    self.index = self.listbox.curselection()
    if self.counter % 2 == 0:
        print("Counter = ",self.counter)
        self.add_index_to_selection(self.index)
    else:
        return