problem with width_for_height

[Detlef Reichl <detlef reichl gmx org>]

Hi,

I have an application, where I get the warning:

Gtk-CRITICAL **:gtk_widget_get_preferred_width_for_height: assertion
'height >= 0' failed

and some times the widgets get wrong widths. It comes from a
Gtk::ComboBoxText that is in this widget hierarchy (from the
ComboBoxText the parents up to the main window):

"Gtk::Box"
"Gtk::Box"
"Gtk::Box"
"Gtk::Frame"
"Gtk::Revealer"
"Gtk::Box"
"Gtk::Viewport"
"Gtk::ScrolledWindow"
"Gtk::Box"
"Gtk::Box"
"Gtk::Window"

Unless the ComboBox isn't shown, the warning does not appear. I do not
change any widget size requisitions by hand in the complete GUI. What is
so special with the combo box and what do I have to honor if I use them?
I've read the docs about "width for hight management" but from my point
of view it only affects own container implementations, which I don't use.

I use gtk 3.14.5 with ruby-gtk from git/master.

I'm very obliged for any hints!
detlef