GTK+ application on dual head

[rona dinihari arkalogic com]

hello to all, i'm rona.

i have a problem with my gtk+ application. i use xmlrpc to send command
and data to this application, which should display on second monitor on
dual head system. it works well on first monitor, but it wouldn't display
when running on second monitor.

i have tried to output some trace. i use GtkLabel, set the text, and get
back the text to see if it has been updated. from the trace it looks ok.
but it still wouldn't display the update.

This is what i use in my xorg.conf:
Section "ServerLayout"
        Identifier     "defaultLayout"
        Screen       0 "Screen0" 0 0
        Screen       1 "Screen1" 0 0
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"
        Option         "Xinerama" "off"
        Option         "Clone" "off"
EndSection

This is the command i use to run on second display:
DISPLAY=:0.1 myapp

How can i fix this?
Why it wouldn't update the display correctly on second monitor?