> Post more complete code. You might be missing a grid() (which is better > than pack()). OK, here's the panedwindow code horizsplit = TkPanedWindow.new(parent) { orient 'vertical' } horizsplit.add(left) horizsplit.add(right) horizsplit.pack( 'fill' => 'both' ) Its failing saying that undefined local variable or method `left' for #<MainGUI:0x403949e8> (NameError) Thanks Nigel