EXT-1803 Fix group inspectors closing before you can see them if you can't join the group.

Focus issue -- the inspector had no focusable widgets in that case.
Reviewed with Richard.

indra/newview/skins/default/xui/en/inspect_group.xml

@@ -73,6 +73,8 @@ L$123 to join
      name="group_icon"
      top="24"
      width="38" />
+  <!-- Must be tab_stop="true" so something can hold focus even when the
+    other buttons are disabled or invisible, otherwise inspector closes -->
     <button
      follows="top|left"
      height="18"
@@ -84,7 +86,7 @@ L$123 to join
      right="-8"
      top="35"
      left_delta="110"
-     tab_stop="false"
+     tab_stop="true"
      width="18"
      commit_callback.function="InspectGroup.ViewProfile" />
   <button