Resolves tdf#155167 - Start center app pane issue under gtk3

Issue introduced with 77ed6380dda73a9716f48f73c3ff730380557a09

Change-Id: I093808b87bca5f93e28239f22886f543a053e62b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/151493
Tested-by: Jenkins
Tested-by: Xisco Fauli <xiscofauli@libreoffice.org>
Reviewed-by: Heiko Tietze <heiko.tietze@documentfoundation.org>
diff --git a/sfx2/uiconfig/ui/startcenter.ui b/sfx2/uiconfig/ui/startcenter.ui
index d8d27b8..4b4cdac 100644
--- a/sfx2/uiconfig/ui/startcenter.ui
+++ b/sfx2/uiconfig/ui/startcenter.ui
@@ -106,6 +106,7 @@
              <object class="GtkScrolledWindow" id="scrollapps">
                <property name="visible">True</property>
                <property name="can-focus">True</property>
                <property name="hscrollbar-policy">never</property>
                <property name="shadow-type">in</property>
                <child>
                  <object class="GtkViewport">