GtkButtonBox style problem

[Vlad Volodin <vest 84 gmail com>]

Hello

If you can, please help me with the next problem:

I have a GtkHButtonBox, where I want to add buttons, as expected. My
buttons should display letters, from 'A' to 'Z'. Buttons' default
width is more than needed (possibly 85 pixels). I've found a function,
to help me:
void gtk_button_box_set_child_size (GtkButtonBox *widget, gint
min_width, gint min_height);

In the help, I saw the message, that the function is deprecated, and I
have to use "the style properties 'child-min-width` and
'child-min-height` instead". But, they are read only:
"child-min-width"   gint : Read
"child-min-height"  gint : Read

Can you help me, what should I do in this case? I've also tried a
simple GtkHBox, and it suits me well, but I think a usage of Button
Boxes are more suitable in my situation.

And also, how to use these style properties: gtk_widget_get_style -->
gtk_style_get_property -- is it the way to read properties, and where
is the way to write them?

Thank you in advance,
Vlad Volodin