Expand the child in the GtkHeaderBar

[Yosef Or Boczko <yoseforb gmail com>]

Good afternoon!

I wrote a program that uses in GtkHeaderBar [1].
In the GtkHeaderBar I put a buttons (GtkButton) and also entry 
(GtkEntry):
entry-without-expand.png [2]:
|<>| |--- entry ---|                                               | X

I tried to expand the entry which is in haderbar, see something like 
this:
entry-with-expand-gimp-editor.png [3]:
|<>| |--------------------- entry ---------------------| | X

To expand, I tired use the following functions:
gtk_widget_set_vexpand (entry, TRUE); /* It does nothing, not expand! */
g_object_set (entry, "expand", TRUE, NULL); /* It also does nothing, 
not expand */
It does not work!

There is a way to expand the entry in headerbar?

I do it so that to port the toolbar in nautilus (NautilusToolbar) to 
headerbar.

[1] attached: main.c or:
https://bitbucket.org/yoseforb/expand-header-bar/src/80a2af720bbc0ef487887d859dcf74410f786267/main.c?at=master

[2] attached: entry-without-expand.png or:
https://bitbucket.org/yoseforb/expand-header-bar/src/80a2af720bbc0ef487887d859dcf74410f786267/entry-without-expand.png?at=master

[3] attached: entry-with-expand-gimp-editor.png or:
https://bitbucket.org/yoseforb/expand-header-bar/src/80a2af720bbc0ef487887d859dcf74410f786267/entry-with-expand-gimp-editor.png?at=master

Regards,
‏Yosef Or Boczko

Attachment: entry-with-expand-gimp-editor.png
Description: PNG image

Attachment: entry-without-expand.png
Description: PNG image