How to unfocus an focused widget

[Jiang XU <jiang xu echostar com>]

If a widget is  focused, I want to unfocus it, what should I do??

One way is using gtk_widget_grab_focus(..) to grab another focus widget,
but I don't want to use this way, I just want to unfocus the widget
which is focused.

If any one knows, please teach me, I really appreciate that.

Thanks