how to set a button's focus?

[=?big5?b?tsC8eSBLYXNvbiBIdWFuZw==?= <kasonhuang kinposh com cn>]

Title: how to set a button's focus?

hi,guys:
could you  tell me how to set a button's focus .
In VC++ ,you could set the buttons focus sequence by "1,2,3,4,......",so how to control the buttons focus with "Tab" in gtk+.

anyone knows?
waiting for your mail back.

Thanks a lot!
kasonhuang kinposh com cn
                                                                               kason