duplicate_pane_button = function(x)
	local w = App.width('clone')+10
	button(Global_state, 'clone', {x=x, y=Menu_top+5, w=w, h=Line_height, bg={r=0.6, g=0.8, b=0.6},
		icon = function(p)
			App.color(Normal_color)
			love.graphics.rectangle('line', p.x,p.y, p.w,p.h, 2,2)
			love.graphics.print('clone', p.x+5,p.y+2)
		end,
		onpress1 = function()
			local new_pane = {
				editor_state = copy_editor(Current_pane.editor_state)
			}
			new_pane.output_editor_state = output_editor_state(new_pane.editor_state)			
			Current_pane_index = Current_pane_index+1
			table.insert(Panes, Current_pane_index, new_pane)
			Current_pane = Panes[Current_pane_index]
		end,
	})
	return x+w+10
end

copy_editor = function(state)
	local new_state = edit.initialize_state(
		Menu_bottom + 20,  -- top
		Safe_height/2-Line_height,  -- bottom
		Menu_left + 50 + Line_number_padding,  -- left
		math.min(100+30*App.width('m'), Safe_width*2/3),  -- right
		Font_height, Line_height)
	new_state.lines = map(state.lines,
		function(line)
			return {data=line.data}
		end)
	Text.redraw_all(new_state)
	return new_state
end