You can make a plugin to suppress it. I’m only a beginner with PHP stuff and plugins, etc., but I took a look at at a plugin called Admin Themer, and used that as a basis for adding a stylesheet to the admin header.
Here’s how your custom plugin might look:
/*
Plugin Name: Suppress upgrade nag
Plugin URI:
Description: get rid of upgrade nag
Version:
Author:
Author URI:
*/
function suppress_update_nag () {
print "<link rel='stylesheet' type='text/css' href='";
bloginfo('template_directory');
print "/suppress_nag.css'";
print " />\n";
}
add_filter('admin_head', 'suppress_update_nag');
?>
This filters the admin_head (used in the admin pages) and adds a link stylesheet in your theme folder called “suppress_nag.css” to the header of the admin pages.
Then, in your theme folder, you put the stylesheet “suppress_nag.css”:
/* disable main update nag
leaves plugin nags alone */
#update-nag, #update-nag a {
display: none;
}
This particular one leaves the plugin nags alone, because I wanted to retain them.
If you look in the wp-admin folder, you’ll find a stylesheet called “wp-admin.css”. That controls the styles for the admin pages. ARound line 554 (I’m using WP 2.6.5), you’ll find the styles for the update nag. In my stylesheet above, I simply told them not to display.
The advantage of doing it this way is that it doesn’t alter any core files — it just filters the head and calls on a stylesheet in your theme folder, which won’t get overwritten when you do upgrade.
You can use this technique to change various css aspects of your admin panels.
Use at your own risk, obviously — there’s an inherent security risk in not using the most up-to-date WP version. Personally, I’m quite aware of what version I’m using, but I didn’t want the nag to be there for editors and authors, etc., and especially subscribers visiting their profile (why the hell should they be told to advise the admin to upgrade?).
