How to catch GTK focus state in gtkrc?

GTK+ 2.x has the follow states: NORMAL, PRELIGHT, ACTIVE, INSENSITIVE, SELECTED for use in GTK themes and I can do things like...

bg[NORMAL] = "#f6f6f6"

.. to change background color when in NORMAL state.

Also, I can change the background image o开发者_如何转开发f a button (when the mouse is over it) by changing the PRELIGHT state image.

But I was not able to find a way to change the button background when the user cycle the focus using the TAB arrow (ie. when a dashed rectangle appears around the button). I want to do this using themes in gtkrc, is this possible ?

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I don't think so. The RC file documentation doesn't even mention "focus", so I don't think it's possible to theme that in this way.