Chrome periodically does not redraw the admin panel after setPinMenu() is called

[deadduck169]

Note: This might actually be a Chromium bug, but the workaround is only 1 line of code.

The setPinMenu() function (located in wp-admin/js/common.js) adds and removes classes from the body element and for some reason Chrome 45.0.2454.85 (64-bit) on Linux and Opera 32.0.1948.25, which both use Webkit sometimes fail to re-render the menu after this function is called. The error does not exist with Firefox. To reproduce, I usually just refresh and then click on the Dashboard link. It ends up looking like this:

I have also attached a small screencast. Fortunately to fix this, just add the line

$body.hide().show(0);

to the end of setPinMenu(), which forces Chrome to redraw it. So it should look something like:

    function setPinMenu() {
        resetHeights();

        if ( $adminmenu.data('wp-responsive') ) {
            $body.removeClass( 'sticky-menu' );
            unpinMenu();
        } else if ( height.menu + height.adminbar > height.window ) {
            pinMenu();
            $body.removeClass( 'sticky-menu' );
        } else {
            $body.addClass( 'sticky-menu' );
            unpinMenu();
        }
        $body.hide().show(0);
    }

[deadduck169]

Actually, now that I think of it, it is probably inefficient to redraw the whole window.body element. You can instead just do

$adminmenu.hide().show(0);

Or maybe selecting a more specific sub-element of $adminmenu if that is more efficient. Something like:

$adminmenu.find("li a").first().hide().show(0);

As long as any changes are made to the menu element, Chrome will redraw it.

[helen]

Hi @deadduck169! This is a really fantastic first ticket. It is a duplicate of #33199, but you've tracked this down in more detail, and it's much appreciated. Chrome should be at 45.0.2454.99 now in stable channels, and this particular issue was fixed in 45.0.2454.93.

[deadduck169]

I'm glad I could help. It really took me a while to track the exact code that reproduces the bug because as soon as a change is made to the page, the menu gets re-rendered correctly. If only I had done a bit more thorough search trying to find the duplicate bug.

Unfortunately it hasn't been pushed to the Google's Debian-based repository yet, but I'm sure it will be soon. Opera, on the other hand, is another story. It will likely be a few months before it gets included there.