load_button = function(x, y, r)
	return overflowable_button('load', x, y, r,
		function()
			Show_file_dialog = true
			File_dialog_callback = function(filename)
				if filename == '' then
					-- clear filename
					Current_pane.filename = nil
					return
				end
				Current_pane.filename = filename
				one_time_load()
			end
		end)
end