Is is possible to set the Max length of a ComboBox in wxruby?

I have looked in the documentation but find nothing
http://wxruby.rubyforge.org/doc/combobox.html

But if i do my_combobox.methods.sort I get set_max_size and set_min_size in the list. But When I call it my_combobox.set_max_length(100) I only get
undefined method 'set_max_length' for #<Wx::ComboBox:0x4d4a914>

I've also tried to call it as a private method

  def my_combobox.max(i)
    set_max_length(i)
  end
  my_combobox.max(100)

But with the same result.

The issue I want to avoid is that if somebody pastes 6000+ characters in my Combobox the text becomes white.