Adding widgets to boxes later?!

[freyd uni-muenster de]

Hello Friends,

till now I found gtk (or better gtk--) programming rather logical, but
now I'm stuck. I have a colormap widget, that shows all colors in a
certian colormap. It has some GtkHBox, that has some GtkButtons packed
into it. Now in some callback I pack another Button into it, but it 
doesn't show up. Depending on whether I set homogeneous, I can also get
quite a mess on the screen.

Only when I resize the Window, the new buttons show up.

I've even tried the draw signal, should be gtk_widget_draw, but to no
avail.

Does anybody know how to do this properly?
I'm using gtk+1.1.16 and gtk---0.11.2.

Well, thank you for any help...

Oliver