Notice "Use of undefined constant MSTBA_DISPLAY_NETWORK_ITEMS" on network update

Hello,

I too have the problem about a notice appearing when I click on network update:
“Notice: Use of undefined constant MSTBA_DISPLAY_NETWORK_ITEMS – assumed ‘MSTBA_DISPLAY_NETWORK_ITEMS’ in /home/xxx/domains/[blog-URL]/public_html/wp-content/plugins/multisite-toolbar-additions/multisite-toolbar-additions.php on line 878”

If I choose to update, WP says it did it, but the above notice still appears and is visible on every page I manage when I select any network admin menu.

My installation is on a shared hosting, WP 3.6 multisite with directories (not subdomain) and the plugin is v. 1.4.0

https://www.ads-software.com/plugins/multisite-toolbar-additions/