room-history: Show focus ring around visual media

data/resources/stylesheet/_room_history.scss

@@ -264,9 +264,14 @@ state-group-row.room-history-row {
   }
 }
 
+message-visual-media {
+  border-radius: vendor.$menu_radius;
+
+  @include vendor.focus-ring();
+}
+
 .visual-content {
   &.opaque-bg {
-    border-radius: vendor.$menu_radius;
     background-color: var(--border-color);
   }
 

src/session/view/content/room_history/message_row/visual_media.ui

@@ -3,13 +3,13 @@
   <template class="ContentMessageVisualMedia" parent="GtkWidget">
     <property name="focusable">True</property>
     <property name="halign">start</property>
+    <property name="overflow">hidden</property>
     <child>
       <object class="GtkOverlay" id="overlay">
         <style>
           <class name="visual-content"/>
           <class name="opaque-bg"/>
         </style>
-        <property name="overflow">hidden</property>
         <child>
           <object class="GtkStack" id="stack">
             <property name="transition-type">crossfade</property>