on.initialize = function(arg)
	if #arg == 0 then
		if Data_dir == nil then
			error('please provide a directory to browse')
		end
	else
		if is_absolute_path(arg[1]) then
			Data_dir = arg[1]
		else
			Data_dir = App.current_dir..arg[1]
		end
	end
	print('reading articles from '..Data_dir)
	if not file_exists(Data_dir) then
		error('no directory '..Data_dir..' found. Please store articles to browse there before opening this app.')
	end
	local comment_path = Data_dir..'/comments'
	if not file_exists(comment_path) then
		App.mkdir(comment_path)
	end
	reset_viewport()
	love.graphics.setFont(love.graphics.newFont(20))
	local font = love.graphics.getFont()
	font:setLineHeight(1.3)
	initialize_file_picker()
	A()
	Viewport.x, Viewport.y = Viewport_bounds.xmin, Viewport_bounds.ymin
	B()
end