refresh the screen before the function end

[WAN Hing Wah <50191914 ee cityu edu hk>]

Hello,
	I wanna know after I change the GdkPixmap stored in GtkPixmap
by gtk_pixmap_set(),how can I ask it to immediately to refresh the screen
the show the effect before the function end?
I am writing a chess game,In a callback function I capture
button_press_event when the user click the chess,then in the function I
do something in the screen inorder for what the user has changed...
but then after it immedialtey I will let computer play the turn in the
same function,so the screen will only be refresh after both the user and
computer play,but I want to show what the player have moved in the screen,
delay,and then let the computer move,how can I achieve it?
if you don't understand,please goto
http://www.ee.cityu.edu.hk/~50191914/gtkapple/gtkapple.tar.gz to try
my program,u will know what I mean...thx......