Despite the name, the test was not in fact showing
contents on map anymore, since widgets are visible
by default. Setting visible to FALSE makes the test
work as expected again.
<signal name="map" handler="gtk_widget_show" object="label1" after="yes" swapped="yes"/>
<child>
<object class="GtkLabel" id="label1">
+ <property name="visible">0</property>
<property name="label" translatable="yes">This label is only shown when the window is mapped. So the window does its first size allocation without the label being visible and has to resize.</property>
<property name="width_chars">20</property>
<property name="wrap">1</property>