Topo2: corrected the highlighting of the bg icon in the toolbar

Change-Id: I57547838e9e4df019c5bf14cc8f008148eae0194
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2Toolbar.js b/web/gui/src/main/webapp/app/view/topo2/topo2Toolbar.js
index 1324029..a0b1b94 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2Toolbar.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2Toolbar.js
@@ -13,7 +13,7 @@
         // H: { id: 'hosts-tog', gid: 'm_endstation', isel: false },
         // M: { id: 'offline-tog', gid: 'm_switch', isel: true },
         P: { id: 'topo2-ports-tog', gid: 'm_ports', isel: true },
-        B: { id: 'topo2-bkgrnd-tog', gid: 'm_map', isel: false },
+        B: { id: 'topo2-bkgrnd-tog', gid: 'm_map', isel: true },
 
         // Z: { id: 'oblique-tog', gid: 'm_oblique', isel: false },
         // N: { id: 'filters-btn', gid: 'm_filters' },