f.pos undefined?

simplified version of my problem

    require 'wx'
Wx::App.run do
  f = Wx::Frame.new nil
  f.title= 'the potlee'
  f.size= Wx::Size.new( 200 , 500)
  f.pos= Wx::point.new(50,50)
  f.show
end

i get this error

`method_missing': undefined method `pos=' for #<Wx::Frame:0x207d020>

how can i set the size on the frame but not the position?

note:using the latest version of wxruby on windows(which came with its开发者_如何学C own ruby interpreter).

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Should you not have a capital P for Wx::Point?