tdf#119931 Fix a11y warnings in classificationdialog.ui

Make "Content" a label for the drawing area

Change-Id: I2238ea42d33564d848376e3c33b9d9a46af094ae
Reviewed-on: https://gerrit.libreoffice.org/72045
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>

solenv/sanitizers/ui/svx.false

 svx/uiconfig/ui/classificationdialog.ui://GtkTreeViewColumn[@id='treeviewcolumn3'] no-labelled-by
-svx/uiconfig/ui/classificationdialog.ui:GtkDialog[@id='AdvancedDocumentClassificationDialog']/GtkBox[@id='dialog-vbox1']/GtkGrid/GtkGrid/GtkLabel orphan-label
-svx/uiconfig/ui/classificationdialog.ui://GtkDrawingArea[@id='classificationEditWindow'] no-labelled-by
 svx/uiconfig/ui/classificationdialog.ui://GtkTreeViewColumn[@id='treeviewcolumn6'] no-labelled-by
 svx/uiconfig/ui/classificationdialog.ui://GtkTreeViewColumn[@id='treeviewcolumn4'] no-labelled-by
 

svx/uiconfig/ui/classificationdialog.ui

@@ -274,12 +274,15 @@
                 <property name="vexpand">True</property>
                 <property name="row_spacing">3</property>
                 <child>
-                  <object class="GtkLabel">
+                  <object class="GtkLabel" id="classificationContentLabel">
                     <property name="visible">True</property>
                     <property name="can_focus">False</property>
                     <property name="label" translatable="yes" context="classificationdialog|label-Content">Content</property>
                     <property name="xalign">0</property>
                     <property name="yalign">0</property>
+                    <accessibility>
+                      <relation type="label-for" target="classificationEditWindow"/>
+                    </accessibility>
                   </object>
                   <packing>
                     <property name="left_attach">0</property>
@@ -341,6 +344,9 @@
                             <property name="can_focus">True</property>
                             <property name="events">GDK_BUTTON_MOTION_MASK | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | GDK_KEY_PRESS_MASK | GDK_KEY_RELEASE_MASK | GDK_FOCUS_CHANGE_MASK | GDK_STRUCTURE_MASK</property>
                             <property name="hexpand">True</property>
+                            <accessibility>
+                              <relation type="labelled-by" target="classificationContentLabel"/>
+                            </accessibility>
                           </object>
                         </child>
                       </object>