Fixed bug LT-85 (Location Response Selections). Work on LT-9 and LT-12

Packages/viewerbase/client/components/viewer/imageViewerViewport/imageViewerViewport.html

@@ -2,7 +2,8 @@
     <div class='imageViewerViewport'
         oncontextmenu='return false;'
         unselectable='on'
-        onselectstart='return false;'>
+        onselectstart='return false;'
+        tabindex='0'>
     </div>
     <div class='viewportInstructions'>
         Please drag a stack here to view images.