Topo2 - Key Command 'H' to toggel hosts visibility
JIRA Tasks; ONOS-6283

Change-Id: Id1b8c00342af799e1d92c84346bb3fe6f6023af6
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2Region.js b/web/gui/src/main/webapp/app/view/topo2/topo2Region.js
index 7ab0b10..7e5c37c 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2Region.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2Region.js
@@ -173,7 +173,18 @@
 
                     return false;
                 },
+                toggleHosts: function () {
+                    var state = this.lookupPrefState('hosts');
+                    this.updatePrefState('hosts', !state);
 
+                    _.each(this.model.get('hosts').models, function (host) {
+                        host.setVisibility();
+                    });
+
+                    _.each(this.model.get('links').models, function (link) {
+                        link.setVisibility();
+                    });
+                },
                 update: function (event) {
 
                     if (!this.isLoadComplete()){