set the image in the .ui instead of the .cxx

Change-Id: Id6c30fa9cad6bbfbfb4e5c1363f637868884b345
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/146792
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

cui/source/options/optgdlg.cxx

@@ -566,7 +566,6 @@ OfaViewTabPage::OfaViewTabPage(weld::Container* pPage, weld::DialogController* p
 
     m_xIconStyleLB->set_active(0);
 
-    m_xMoreIcons->set_from_icon_name("cmd/sc_additionsdialog.png");
     m_xMoreIcons->connect_clicked(LINK(this, OfaViewTabPage, OnMoreIconsClick));
     m_xRunGPTests->connect_clicked( LINK( this, OfaViewTabPage, OnRunGPTestClick));
 }

cui/uiconfig/ui/optviewpage.ui

@@ -9,6 +9,11 @@
     <property name="step-increment">1</property>
     <property name="page-increment">10</property>
   </object>
+  <object class="GtkImage" id="image1">
+    <property name="visible">True</property>
+    <property name="can-focus">False</property>
+    <property name="icon-name">cmd/sc_additionsdialog.png</property>
+  </object>
   <!-- n-columns=2 n-rows=1 -->
   <object class="GtkGrid" id="OptViewPage">
     <property name="visible">True</property>
@@ -450,9 +455,8 @@
                     <property name="can-focus">True</property>
                     <property name="receives-default">True</property>
                     <property name="tooltip-text" translatable="yes" context="optviewpage|btnMoreIcons">Add more icon themes via extension</property>
-                    <child>
-                      <placeholder/>
-                    </child>
+                    <property name="image">image1</property>
+                    <property name="always-show-image">True</property>
                   </object>
                   <packing>
                     <property name="left-attach">2</property>