displaying xpm image on a button - why this warning?

[Jang JaeIk <cji dmc htc hanwha co kr>]

Hi all.

I want to display xpm image on a button . So, I test a example of chap.
6 in gtk tutorial (I attatch it xpm_button.c). and then complie it and
run it. but such an warning occured.

** WARNING **: Creating pixmap from xpm with NULL window and colormap

why this warning is occured? & what shall I do remove it?
I use gtk1.0.5

T.I.A.