Core Update nag on dashboard, Indicators on admin menu, admin bar or toolbar, dismiss.
Maintenance Mode., when it's activated, or automatically, if it's in mu-plugins directory..
neat trick, is to put this single file dismiss-update-nag php in the wp-content mu-plugins directory so you won't even have to enable it, and will be loaded by default, also, since first step installation of WordPress setup..
The code of this plugin, is not written with framework, but with simple php editor, manually, UTF-8 without BOM, and Unix LF.
To avoid code corruption, do not edit it with WordPress embedded editor, or with any specifications incompatible editor..
Thanks to Andrea Gandino for Italian translation approval..
Thanks to Garrett Hyder for English translation approval...
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