server:
CentOS 7.x x86_64
MariaDB 10.1.9
PHP 7.0.0
MantisBT 1.3.0-rc1

client:
Windows 7
Chrome and IE

wrong web page layout, please check the attached screen dump. and no file upload.

config:
$g_allow_file_upload = ON;
$g_file_upload_method = DISK;
$g_absolute_path_default_upload_folder = '/opt/www/html/public/upload/';
$g_max_file_size = 5000000;
$g_preview_attachments_inline_max_size = 256 * 1024;