The two volume buttons are supposed to be
vertically arranged.
<property name="valign">center</property>
<property name="value">.5</property>
<property name="halign">center</property>
+ <layout>
+ <property name="left-attach">0</property>
+ <property name="top-attach">0</property>
+ </layout>
</object>
</child>
<child>
<signal name="query-tooltip" handler="on_scale_button_query_tooltip" swapped="no"/>
<signal name="value-changed" handler="on_scale_button_value_changed" swapped="no"/>
<layout>
+ <property name="left-attach">0</property>
<property name="top-attach">1</property>
</layout>
</object>