GtkContainer Gtk 3.0 vs Gtk 3.2 geometry management

[Denis Linvinus <linvinus gmail com>]

Hi all,
i'm writing new GtkContainer which allocate children, firstly horizontally, then vertically. - HVBox.

On gtk 3.0 it works without problems (with little trick), but with gtk 3.2. window don't change height when container change, until i move mouse above my container.

My idea is that my container should use minimum space as possible, but enough to show all children.
If available width not enough for children then container should increase height  for second line, and so on.
Something like multiline tabs in firefox. (children is a buttons)

There is my sources http://pastebin.com/8qugyfqk (i use valac --pkg gtk+-3.0 -C ./main.vala to compile)

image with  explanation of the problem http://imageshack.us/photo/my-images/508/resulte.png/
there is two control buttons (add, remove) in one VBox, all other buttons  in my HVBox container. 
As you can see at last screenshot, i lost two buttons after resize window on Gtk3.2, if i move mouse on buttons again then window will change it height , so that the lost buttons will be visible.

I'm check, problem is not in vala, i use generated *.c from ubuntu 11.10 to compile on Ubuntu 11.04 without modifications, and it also works correctly.

May be someone know how to force window to recalculate size?
Or some other method to resolve my problem?

My system ubuntu 11.10 
libgtk-3-0  3.2.0-0ubuntu3

Ubuntu 11.04 for Gtk 3.0
libgtk-3-0  3.0.8-0ubuntu1

I will appreciate for any help.
p.s. sorry for my English.