Focus Ring on jQuery UI Dialog Button

I've got a jQuery dialog box with a button to close it. The button has focus when the dialog box opens. The problem is that the focus 开发者_开发知识库is a dotted line around the button's text instead of a focus ring around the entire button. I'm using jQuery's smoothness theme.

I'm using the dialog in a WordPress plugin.

My code is:

$('#mydialog').dialog({
        title: 'My Title',
        position: [619,200],
        resizable: false,
        buttons: {"OK" : function(){$(this).dialog("close");}}
    });

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The problem may relate to the browser; the way each browser highlights the focused element differs.