Maximum window width

[Goran =?utf-8?q?Raki=C4=87?= <gox devbase net>]

I know how to implement minimum width, but how to implement maximum width. If 
I turn off resize function, than both width and height will be locked to 
prefered values. But, I want only width to be fixed as I have some pixmap in 
window "header" and window mustn't be wider than that pixmap.

Thanks,
Goran Rakic